POISON APPARATUS OF VENOMOUS SNAKES 63 



fresh gland the tubules are sometimes filled with the secretion (venom), 

 which appears as clear, transparent particles. The lymphatic space of the 

 secretory duct gradually disappears near the end. Niemann (1892) and 

 Lindemann (1899) observed that the tubular arrangement of the poison 

 gland of Vipera berus is of irregular nature and to be considered as a second- 

 arily modified tubular gland. 



While Leydig and Reichel described the epithelia of the poison gland as 

 low and cylindrical, Niemann and Lindemann found them to be cubic. Yet 

 the study of the latter authors revealed the cause of this difference. They 

 found that in the epithelium immediately after the bite the nuclei are dark, 

 stainable, not larger than half the diameter of the basis of cell, and stand 

 slightly apart from the base. The granulation is gradually increased toward 

 the upper part and thickest near the free edge of the. epithelium. In a snake 

 which has been kept a long time in captivity and has not bitten for some 

 time the granulation is much lighter and more regularly and evenly distributed 

 throughout the cell-body. The approximate size of the cell remains, how- 

 ever, unchanged. 



THE PROCESS OF SECRETION OF VENOM. 



The process of secretion is comparable to that of salivary secretion. In 

 the protoplasma of the epithelium homogeneous droplets appear and render 

 the protoplasma more transparent. Immediately after secretion of the 

 venom the periphery of cells becomes more darkly granulated. 1 



According to a later study of Launoy 2 (1903) the process of venom secre- 

 tion can be divided into two phases: (i) a phase of nuclear elaboration, (2) a 

 phase of cytoplasmic elaboration. 



Besides the passive exchanges which take place between nucleus and cyto- 

 plasma, the nuclear sphere participates very actively in the secretive process. 

 This participation of nucleus is evident from the following reactions: 



(1) By the difference in the stainability of the chromatin grains. 



(2) By emission of equal-sized, spherical, well-defined grains, with tincto- 

 rial reaction of the internuclear differentiated chromatin, into cytoplasma. 



(3) By the exosmosis of the dissolved nuclear substance, which appears 

 in the meanwhile in ergastroplasmic form. 



These formations constitute, on the one hand, the grains of "venogene;" 

 on the other, the "ergastroplasmic venogene." 



In the venom cell of Vipera aspis and the serous cell of the parotid of 

 Tropidonotus natrix is produced chiefly in a granular form. 



After reaching to the perinuclear cytoplasma the venogene grains and 

 ergastroplasmic venogene will at once disappear, if it happens to be during 

 the period of cellular excitement; or will remain for some time, if it is at a 

 period when the cell is saturated with the product. During the cytoplasmic 

 activity the venogene grains and ergastroplasmic venogene disappear. 



1 Lindemann. 



a Launoy, These de doctorat es sciences, Paris, 1903, No. 1138, serie A, 454. 



