THE MALE-CELL OR SPERMATOZOA A r . 103 



CHAPTER IX. 



THE MALE-CELL OR SPERMATOZOAN. 



I. The General Contrast between Ovum and Sperma- 

 tozoan. — Just as the ovum — large, well nourished, and passive — is 

 a cellular expression of female characteristics, so the smaller size, less 

 nutritive habit, and predominant activities of the male are summed up 

 in the sperm. As the ovum is usually one of the largest, the sperm 

 is one of the smallest of cells. The yelk or food-capital, and encysting 

 membranes, which are often so prominent in the former, are as con- 

 spicuously absent in the latter. The contrast, though less accented, 

 is still quite discernible in plants. In fact, the two kinds of cells are 

 just as widely opposed in their general features as they are funda- 

 mentally complementary in their history. Before this opposition and 

 complementariness can be fully understood, however, we must briefly 

 sum up the characters and history of the male elements. 



II. History of Discovery. — In 1677, one of Leeuwenhoek's students, 

 Hamm by name, called his master's attention to the minute elements actively 

 moving in the male fluid. Leeuwenhoek, who some years previously for the 

 first time observed what we now know as unicellular organisms, was at once 

 impressed by the import of the marvelously active male units. Almost too 

 much impressed, in fact, for he interpreted them as minute preformed germs, 

 which only required to be nourished by the ovum to unfold into embryos. Thus 

 the unfortunate aberration, already noted as the doctrine of the" animalculists, 

 had its origin. For long no progress whatever was made ; some naturalists, like 

 Vallisneri, depreciating the import of the sperms altogether, and regarding them 

 as worms which hindered the coagulation of the seminal fluid ; others going to 

 the opposite extreme, and regarding them as nests of germs. Thus Haller at 

 first considered them to be what Leeuwenhoek had suggested, but afterwards 

 admitted them merely as nativi hospites seminis. In 1835, even Von Baer was 

 inclined to interpret them as minute parasites peculiar to the male fluid ; and if 

 the curious student will turn up the article " Entozoa " in Todd's Cyclopccdia of 

 Anatomy and Physiology, of about the same date, he will find that the veteran 

 Owen includes the spermatozoa under that strange heading. The very name 

 spermatozoan recalls the view which so long prevailed. 



In 1837, R. Wagner emphasized their constancy in all the sexually mature 

 males which he examined, and their absence in infertile male hybrids ; Von 

 Siebold demonstrated their presence in many of the lower animals ; and lastly, 

 in 1 841, Kolliker made one of his many important contributions to biology, in 

 proving that the sperms had a cellular origin in the testis. 



III. Structure of the Sperm. — The sperm, then, is a cell. 

 Though some, such as Kolliker, have inclined to regard it rather as a 

 nucleus, its truly cellular character may be regarded as proven beyond 



