EFFECTS ON THE HIGHER INVERTEBRATES 



55 



nounced; all nuclei are now small and variably pycnotic. The changes during 

 hibernation are somewhat similar, but slighter, and there is no cytoplasmic 

 atrophy, probably because of the preparatory period preceding hibernation. 

 Krahelska later ('12, '13) studied thoroughly the histological changes in 

 the albuminous gland (accessory gland of the hermaphroditic sexual duct) 

 of Helix pomatia and Helix arbustorum during inanition and hibernation. In 

 Helix pomatia, during five or six months of total inanition, with loss of 40 



55 



50 

 45 

 40 



s 



530 



S 



I 



10 

 15 

 10 

 5 

 



(-J 



10 12 14 



Weeks of Inanition 



Id 



18 



10 



a. 



Fig. 26. — Chart showing the changes in the volumes of entire gland-cell, cytoplasm and 

 nucleus, in the albuminous (accessory sexual) gland of the snail. Helix pomatia during inani- 

 tion up to a period of twenty-two weeks. (From Krahelska '13.) The volumes were esti- 

 mated by projecting the magnified cells in sections upon paper, and measuring the correspond- 

 ing average areas of cell, cytoplasm and nucleus. There is a marked and progressive decrease 

 in the entire cell and the cytoplasm. The nucleus decreases but slightly, however, which 

 causes a marked rise in the nucleus-plasma ratio. 



per cent (or more) in body weight, the non-glandular sexual ducts are not 

 greatly atrophied, but the albuminous gland undergoes reduction to about one- 

 half in length. The color of the gland also changes from milk-white to yellow, 

 later orange-brown. The individual gland-tubules show marked atrophy 

 (Fig. 27). The corresponding progressive decrease in the size of the cells, 

 together with changes in the relative amount of nucleus and cytoplasm, are 

 shown in Fig. 26. It is evident that the cytoplasm decreases much more rapidly 

 than the nuclei, resulting in a marked increase in the nucleus-plasma ratio. 

 The "parenchyma" (stroma) nuclei, which at first are only half as numerous as 

 the glandular epithelial nuclei (in a given field) proliferate by amitosis and become 

 more abundant, finally becoming almost equal to the glandular nuclei in number. 

 The cytoplasmic changes during inanition (Figs. 27, 28, 29, 30) may be 

 roughly classified in two stages. (1) During the phase of "reduction," the cells 

 become undifferentiated, and return to a somewhat embryonal condition (Fig. 



