OF GENERATION. 333 



which those appendages are entirely wanting, as well as, vice versa, 

 their significant size necessarily contradicts the opinion that they are 

 unimportant to the function of generation. 



With regard to the appendages of the male organs, their analogy to 

 Cowper's and the prostate gland bespeak in some degree their 

 importance to impregnation. They contain a fluid which is thinner 

 than the semen, sometimes perfectly hyaline, but yet of a viscous 

 nature. This fluid pours itself out at the same time as the semen; 

 consequently, after copulation, the gluten organs become lax and flaccid, 

 whereas, previously, they were tense and turgid. Suckow therefore 

 supposes that the gluten merely increases the quantity of the semen by 

 rendering it more fluid, thereby giving it a general distribution, which 

 promotes the impregnation of the eggs. Burdach * considers this also 

 as the function of the prostate and Cowper's glands. 



The secretion of the female appendages is not the same as that of 

 those of the male ; it consists of a thicker, more viscous, yellow liquid, 

 which is not, as the former, poured out at the time of copulation, but 

 subsequently upon the passage of the eggs through the vagina. It is 

 here that the eggs are covered with this gluten, and are thereby affixed 

 to their place of deposition, for example, to the leaves and twigs of 

 plants. Many eggs derive their peculiar form from this coating, for 

 example, the long pedicle of the egg of Hemerobius ( PL I. f. 14.) is 

 formed by this glutinous coat ; it is also what connects together the eggs 

 of Gastrophaga Neustria. The organs secreting this gluten are 

 deficient in those insects which deposit their eggs immediately in or 

 upon the food of the young, as for example, in the Ichneumons, many 

 flies, the Tenthredos and Cynipsodea, and many others, although not 

 yet proved by inspection. 



A second function may consist in lubricating the vagina during 

 copulation, or the tube of the oviduct upon the passage of the eggs, and 

 thereby facilitating both processes ; at least, in some instances, for 

 example, in the Lepidoptera, we observe two different appendages, the 

 smaller one of which may possibly fulfil this function, and the other 

 larger one accomplish the first. By means of this gluten, thus generally 

 distributed throughout the egg ducts, the passage of the male semen 

 from the spermatheca to the egg tube may be facilitated and promoted. 



* Physiologic, vol. i. p. 460. k. 



