"But in South Africa wild animals are found in abundance on the plains."

"True; but they have very thick brush, or cover, owing to the luxurious growth of vegetation. That affords them means for covering their retreat when attacked."

Following out the usual custom while on expeditions of this kind, they constantly, while on the way, stopped to examine specimens of plants and trees.

[Ill.u.s.tration: _Fig. 12. Branch of the Camphor Tree._]

"Here is a branch, with the flower, of a tree, and the smell is very familiar."

"That is from a camphor tree; do you not recognize it?"

"So it is; I know camphor is good for a great many things."

"It would take some time to enumerate the things camphor is used for.

Indeed, there are so many that Raspail, a French chemist, years ago found a system of medicine largely on the camphor plant, claiming that it was nature's universal remedy."

"Here is a sample of plant which we found growing in bushes; there were also a few trees with the flowers. It is bitter to the taste."

"This is the Calisaya, one of the varieties of the plant from which the well-known quinine is made. There are at least forty varieties of the plant. This is indeed a valuable find. But I see you have some beans there?"

"Yes; are they good to eat?"

"In South America, particularly in the Argentine Republic, it is eaten as a fruit, and the seeds are fed to cattle. Our yaks would relish them."

"We saw them everywhere on the other side of the river."

"The dry pulp of the seed is very nutritious, and is supposed to have been the food of St. John while in the wilderness, as it is the same kind of locust bean that grows in Palestine, and in various parts of Asia Minor. The Spanish name is Algoraba, or Carob-tree."

"We have brought only one more sample, and it looks very familiar, but I never saw any beans or pods on it like this."

"Don't you recognize Smilax? Of course, it is somewhat different from the kind you know. The root of this kind of Smilax is called Sarsaparilla, and the bean is good to eat."

"Well, I am going to lay in a supply."

The boys could not forget the animal they had shot when morning came, so at the Professor's suggestion, they improvised a raft, which was loaded on the wagon, and a start made for the river.

Tethering the team the raft was launched, and the Professor accompanied them across. A light skid had been made for use in transporting the hide, so they would not be compelled to carry it the entire distance.

Before they had reached the spot pointed out by the boys, they stumbled on the animal.

"Why," said the Professor, "this is an Ocelot, very dangerous when attacked, and just the kind of beast to elude you. I commend you for the good judgment in adopting the course you did."

"See here, Harry; I don't understand this. You will remember when we examined him, just before leaving him here, that we found only one bullet hole between the shoulders; this has two bullet wounds, one in the head and the other in the neck."

"Why this is not the place we shot him. This must have been shot by some one else."

"Do you remember what you selected as your marking for the spot?"

Harry looked about, and finally said: "I remember two trees, standing about ten feet apart, east and west of each other."

"That is the place, I am sure," was George's conclusion, after they had made a circuit around the spot; "yes, I am sure those are the trees."

"There it is; I see it."

Surely enough, close to the two trees an animal was found, larger than the one they had just left.

"So it seems you killed two of them," and the Professor was so much amused he could not help laughing as he saw the amazement on the boys'

countenances. "You are certainly fine hunters."

"I think--yes; here is the shot in the shoulder--this is the last one we shot. The other one, over there, was the one we followed so long and took our first shot at."

Within two hours the skins were ready, packed on the skid, and delivered at the raft, and after a hard forenoon's work the Cataract was reached shortly after noon.

CHAPTER VI

HUNTING VEGETABLES AND PLANTS

One night, while engaged in the usual evening discussion, many topics were mentioned, things connected with the day's adventures talked over, and plans for the following day considered.

As usual, George was the persistent questioner, but Harry was the one to utilize the meaning, and generally the first to take advantage in a practical way of the information thus obtained.

We have stated heretofore that George was the theorist and Harry the practical one. George delighted to delve down into mysteries; but Harry utilized the knowledge in constructing and building articles. Both, therefore, had useful accomplishments. To learn and to do are the great things in life.

During the day the boys had turned out a nice sample of bread, and George, as usual, began the questioning:

"Professor, you said the other day, that fermentation caused a change in the dough, and that it was due to heat. I am curious to know why heat should cause it to ferment?"

"Heat develops bacteria, a tiny germ, which grows so rapidly in a short time, that millions are produced. These living organisms cause gases to form, and they continue to breed and grow and multiply so long as they have anything to feed on."

"And we eat all that stuff and call it good?"

"Yes; and why not? Every part of your body contains the little creatures, and they really keep you alive, and preserve your health, as well as prevent diseases."

"Why so?"

"Most germs are of the harmless type, and it is because of the vast numbers of the harmless ones that the few poisonous or disease germs are killed. Water has millions of them in every cubic inch. Professor Dewar, a great English chemist, calls them nature's policemen. If a typhoid fever germ, for example, should be introduced among so many germs, as is the case every day, a fight at once takes place, and where a person is finally attacked with the fever, it is because the germs escaped the policemen who were on duty."

"That sounds like a romance."

"Yes; the life history of those germs is really a wonderful thing, and books have been written about them. They exist in tribes, as it were; some of them can live only where oxygen is present, and some live on nitrogen only; others on carbon. But that is not all. Man has learned to use them, so they will work just as surely as our yaks work for us under our direction."

"How interesting! In what way do we use them?"

"In what is called the septic system of treating sewage. You know that sewage from the kitchen contains all kinds of meat and vegetables, and the more it has fermented the stronger becomes the odor and the greater are the number of bacteria in the sewage. The sewage in the liquid state is first placed in a reservoir, and at a certain temperature the germs grow very rapidly, and, of course, eat up the vegetable and animal matter until it is nearly all consumed. Then it is run off into another reservoir which has another tribe of germs in it, those that live on carbon, and which are not harmful to man, and when these two tribes meet war is declared, and they fight to the death. The harmless germs are victorious in every battle, and when the sewage is discharged into a stream, or used for irrigating purposes, few, if any, of the harmful germs remain."

"So in using germs the object is to cultivate one kind to kill another kind?"