1890-9 J.] AMPHIBIA BLOOD STUDIES. 241 



the yolk-hoIding ova may be derived from this source. It is somewhat 

 difificult, otherwise, to explain the process of respiration in larval Anibly- 

 stoniata which pass a week or more i in bedded deeply in gelatinous masses 

 floating in stagnant ponds. 



I have seen, in a few cases, the straw-yellow crystal-like bodies in the 

 immediate neighborhood of the nuclear membrane as Cuenot* has de- 

 scribed. I have represented in Fig. 26 the arrangement of the bodies 

 but they are not always as closely applied to the nucleus as there shown, 

 for they, in the greater number of cells in which they were found, lie free 

 in an apparently empty space between nuclear and cell membranes. I 

 regard all these cells, as well as those described by Cuenot — who believes 

 that they indicate the secretion of haemoglobin from the nucleus — as the 

 products of pathological conditions. I have not seen more than half a 

 dozen of such cells and yet I have diligently examined the fresh blood 

 of several hundred larvae in various stages of development. 



Research demonstrates more and more the influence which the nucleus 

 exercises on the nutrition and function of the cell and among the obser- 

 vations put forward in this line those of Korschelt-f- may be mentioned, 

 in which it is shown that the formation of chitin is directly dependent 

 on the nucleus. Among the covering cells of the ova of Nepa and 

 Ranatra the nuclei of two fused cellular elements approach each other and 

 enclose between them a cavity in which chitin is deposited. PlatneriJ: 

 also considers that the derivation of enzymes in gland cells takes place 

 by the constriction and separation of a portion of the nucleus and the 

 subsequent formation of zymogen granules at the same time that the 

 chromatin of the separated nuclear portion is undergoing degeneration 

 and absorption in the cytoplasma. He believes that there is a direct 

 causal relation between this budding of the nucleus with the subsequent 

 degeneration of the separated part and the formation of zymogen 

 granules. I have failed to find that Platner's description is true so far 

 as formation of zymogen in the pancreatic cells of amphibia is concerned, 

 but I have found, nevertheless, that the nuclei of these cells play a very 

 important part in the elaboration of the zymogen. It is, also, evident 

 from the trend of researches in vegetable cytology that the nuclei of green 

 cells are the important factors in the elaboration of carbohydrates and 

 that the latter are converted into starch in the chlorophyll grains. § 



*Comptes Rendus. 1888. p. 673. 



tUeber einige interessante Vorgange bei der Bildung der Insekeneier. Zeit. fiir Wiss. Zool., 

 Bd. 45- 



+ Arch. furMikr. Anat., Bd. XXXIII. p. 180. 



§ See on this point Strasburger's Histologische Beitrage. Heft I.: Ueber Kern und Zelltliei- 

 lung im Pflanzenreiche, pp. 194-204. 



