946 SUMMARY OF CURRENT RESEARCHES RELATING TO 



frequently exhibiting cilia for instance, as in the salamander and in 

 man. 



When the blood leaves the vessels, the cytozoa leave the corpuscles 

 and melt away in the fluid. The blood must therefore bo fixed by a 

 special method (not noted). 



In discussing the import of these elements, Prof. Gaule proposes 

 two questions : — (1) What role do they play in the life of the organism ? 

 and (2) From what cells do they originate, and what cells do they 

 become ? Their history, according to Gaule, is as follows : — In the 

 spleen, and exceptionally in the liver, they leave the red blood-cor- 

 puscles, and find their way into certain cells rich in protoplasm, which 

 Gaule terms " nurse-cells." Groups of these nurse-cells lie scattered in 

 the frog spleen like the follicles in the spleen of mammals. The groups 

 increase greatly in size, and their appearance becomes altered. The 

 nigrosinophilous protoplasm becomes filled with granules of a peculiar 

 pigment formed from that of the blood. During this process the 

 protoplasm exhibits a beautiful iron reaction with ferrocyanate of 

 potassium. In these nurse-cells the young blood-corpuscles originate, 

 and the whole process lasts from autumn to spring. 



While the new corpuscles are thus in making, the old ones from 

 which the cytozoa have migrated; gradually die. The quantity of 

 blood decreases gradually throughout winter, and the process can be 

 experimentally regulated, by poisoning with pilokarpin, or merely by 

 the variable environmental influences of imprisonment. The unwonted 

 warmth, dryness, and light form an artificial springtide to the frogs, 

 and the blood-manufacture goes on apace. Instead of red, white 

 corpuscles may also be formed from the cytozoa. In the former case, 

 the cytozoa secrete a fatty substance, which forms an enveloping 

 layer, at the borders of which the pigment appears. In the latter 

 case, the cytozoa break up, within the nurse-cells, into their three 

 main constituents already noted. From each of these a cell may 

 arise. 



In summer, when the frog is eating industriously, blood-corpuscles 

 are formed in quite another way. The phenomenon occurs only in 

 sexually mature frogs, differs in the two sexes, and is associated with 

 the sexual decoration of the skin. It is probable that the cytozoa 

 stand in some direct connection with the sexual function. Dr. 

 Miescher has shown in the case of the salmon, that during the fasting 

 period, the blood is detained in the spleen, and peculiar modifications 

 occur in the muscles, which lead finally to certain constituents of the 

 muscles being utilized for the elaboration of the sexual organs. So 

 in the frog, peculiar modifications occur during the fasting period, 

 which lead to this — that portions of the striped substance pass into 

 the nuclei within which peculiar cells are formed. These cells pass into 

 the blood, reach the liver, where they become modified, their contents 

 passing into the protoplasm of the liver cells. It is then that the blood- 

 corpuscles show the first trace of cytozoa. The elements originating 

 in the muscles, evoke the formation of cytozoa, and are destined for 

 the elaboration of the sex-products. The cytozoon is an individual 

 which unites the constituents for the other tissues of the body. It 



