18 CELL THEORY BEFORE 1860 GOODSIR. 



1. A true secretion i.e., matter formed in the primary se- 

 creting cell cavities ; 2. A mixture of fluid formed in these cell 

 cavities, with the developed or undeveloped nuclei of the cells 

 t hemselves ; and, 3. It maybe a number of secondary cells passing 

 out entire." These he supports by observations on the testicles 

 of the Squalus cornubicus, which show a continual production 

 of cells within cells, which become developed into complete 

 spermatozoa and are thrown off, the glandular parenchyma 

 being in a constant state of change, contemporaneous with and 

 proportioned to the rapidity of the secretion ; therefore " there 

 are not, as has hitherto been supposed, two vital processes 

 going on at the same time in the gland, growth and secretion, 

 but only one, viz., growth the only difference between this 

 kind of growth and that which occurs in other organs being, 

 that a portion of the product is from the anatomical condition 

 of the part thrown out of the system" (p. 422). 



In 1845 he adds the following : 



" I have also had an opportunity of verifying, and to an ex- 

 tent which I did not at the time fully anticipate, the remark- 

 able vital properties of the third order of secretion, referred to 

 in the memoir to which I have just alluded. The distinctive 

 character of secretions of the third order is, that when thrown 

 into the cavity of the gland, they consist of entire cells, instead 

 of being the result of the partial or entire dissolution of the 

 secreting cells. It is the most remarkable peculiarity of this 

 order of secretions that after the secreting cells have been 

 separated from the gland, and cast into the duct or cavity, and 

 therefore no longer a component part of the organism, they re- 

 tain so much individuality of life, as to proceed in their deve- 

 lopment to a greater or less extent in their course along the 

 canal or duct, before they arrive at their full extent of elimina- 

 tion. The most remarkable instance of this peculiarity of 

 secretions of this order is that discovered by my brother, and 

 recorded by him in a succeeding chapter. He has observed 

 that the seminal secretion of the decapodous crustaceans un- 

 dergoes successive developments in its progress down the duct 

 of the testis, but that it only becomes developed into sperma- 

 tozoa after coition, and in the spermatheca of the female. He 



