108 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
which they were familiar; for the spermatozoa were regarded as real 
independent animals and often looked upon as parasites. Attempts 
were even made to classify them, some regarding them as Infusoria 
(Ehrenberg), others as worms. Thus to quote the same author: “It 
is wonderful to consider the minuteness of these little animals, and 
particularly the amazing slenderness of their Tails; which must, not¬ 
withstanding, be furnished with as many Joints as the Tails of larger 
creatures, since they are able to move them with great Agility; and, 
besides, every one of these Joints must be provided with its proper 
Muscles, Nerves, Arteries, and Veins; and also with Fluids circulating 
thro’ them, and supplying them with Nourishment, Strength, and 
Motion. In short, the mind loses itself in contemplating a minuteness 
beyond all human conception; tho’ Reason tell us, it certainly 
must be.” 
Notwithstanding this conception of spermatozoa as animals, samen- 
thierchen, as they were called, no effort seems to have been made to 
trace their origin and development. For this, their methods were 
altogether too crude. The true idea of the spermatozoon being a 
cell could not, of course, be entertained before the announcement of 
the cell theory. The very able discussion of this theory by Schleiden 
(’ 38 ) and Schwann ( 39 ) gave a new impetus to the study of tissues, 
though the cell nature of tissues was already known through the 
researches of Robert Brown, Unger, and others. 
It was not before the year 1840 that it became known that these 
were not animals in a true sense having an individual life of parasitic 
worms, but rather were gradual formations from undifferentiated 
cells. 
Duvernoy gave them the name of spermatozoids or zoosperms. 
R. Wagner (’ 36 ) is thought to have published the first work dealing 
especially with spermatogenesis. He studied the spermatozoa of 
birds. Peltier (’ 38 ), Hallmann (’ 40 ), Dujardin (’ 37 ), and von Siebold 
(’ 36 ) made more or less important contributions also. 
That branch of cytology which we call spermatogenesis really 
began with the first work of Kolliker (’ 41 ). He described the sperma¬ 
tozoa of several invertebrates, replacing the name samenthierchen 
with samenfaden. He showed that they are developed from the cells 
of the testis, but he thought that the nucleus was primarily involved. 
He was doubtless influenced by the theory of a cytoblastemaof Schwann 
which assumed that the nucleus or even the nucleolus is first to arise. 
