430 ANNUAL EEPOET SMITHSONIAN INSTITUTION, 1912. 



them, in spite of the unnatural conditions, in such a state of health 

 that they will undergo reproduction even while in captivity. On 

 account of the short period of life and rapid sexual maturity, no great 

 difficulties were encountered while using these lowly-organized 

 animals. Among the plants, the gardeners and farmers have always 

 looked to it that the technical problems pertaining to these were 

 placed in their hands, even before experimentation, and the study of 

 life phenomena upon the living object was undertaken by biology. 

 A lesser consideration was bestowed upon the animals, especially the 

 so-called "cold-blooded" vertebrates. Zoological gardens contained 

 only mammals and birds. The use of aquaria and teiTaria as a pas- 

 time, which later on lent much assistance to the rearing of organisms 

 for scientific purposes, was still in its infancy, when, with their aid, 

 easily solved problems began to play a part in biology. They also 

 play a part when it is desired to change the normal conditions under 

 which an organism exists. While the botanist often knows, almost 

 instinctively, how he must treat a plant which he receives for the first 

 time, the zoologist, on the other hand, stands almost helpless, though 

 dealing with much better known forms, when he finds them dying on 

 his hands. For my own experunents I had selected charges which 

 demanded considerable attention, and I had to arrange a special 

 technique, step by step, to make it possible to keep these animals, 

 mostly reptiles and amphibians, alive and to have them multiply. 

 Owners of vivaria, who may be among my listeners, may answer that 

 it is not at all difficult to keep a treetoad, toad, or salamander for 

 years in very simple surroundings — a small box with moss and some 

 water. This is very true, but such animals will never multiply under 

 such conditions, although they may live a long time. Furthermore, 

 such conditions would have hardly helped me, for example, to still 

 have living midwife toads (Alytes ohstetricans) , which I collected in 

 Appenzell in the summer of 1894, and some fire salamanders (Sala- 

 mandra maculosa) , which I have had since I was 12 years old, or more 

 than 18 years. The difficulties reach their zenith when one con- 

 siders the problem of keeping a shade and moisture loving salamander, 

 in brilliant light, on dry sand and colored paper, placing only a small 

 vessel with water and a very small nest of moist moss at its disposal, 

 or when one takes care of a lizard, which normally loves dryness and 

 sunlight, in comparatively cool, moist, and dark surroundings. 



Formerly I succeeded in getting the animals experimented upon to 

 reproduce out of doors in so-called out-of-door terraria, or large cement 

 basins. The greater number of these pets have now become domes- 

 ticated, and they perform these functions in smaller containers in- 

 doors. 



And now to the experiments themselves, for I intend to give you 

 a somewhat more complete account of my rearing of the midwife 



