557 
(F. Meves), and a few other instances. In others one form of male 
gamete undergoes more or less complete suppression in the course of 
the spermatogenesis, thus in Cicada tibicen (E. V. Wırcox), Bufo cala- 
mita (von LA VALETTE Sr. GEORGE), Hyla (von La VALETTE St. 
GEORGE), Bombinator (Ivar Bromay), etc., the degree of degeneration 
varying in different cases). Though never of functional value, unless 
it take the place of the ordinary form of sperm, the second kind of 
spermatozoon is probably always represented by something in every 
Metazoan spermatogenesis, its development must at least be initiated, 
but it may be arrested anywhere in the history of the spermatogonia 
or spermatocytes'). It has been described by more than a dozen 
1) Since the above was written the two following papers have 
appeared: Nins Houmeren, Ueber den Bau der Hoden und die Sper- 
matogenese von Staphylinus (a Coleopterous insect, allied to the dung- 
beetles), Anat. Anz, V. 19, No. 18, 27th June, 1901, p. 449—461, 
5 figs. In this paper the author records for this insect two sorts of 
spermatogonia and two categories of spermatozoa. 
F. Meves, Ueber die sog. wurmförmigen Samenfäden von Paludina 
und über ihre Entwickelung (vorgetragen im Physiologischen Verein 
in Kiel am 20. Mai 1901), Separatabdruck aus: Mitteil. f. d. Verein 
Schlesw.-Holst. Aerzte, Jahrg. 10, No. 1, 1901, p. 1—11, also under 
the same title and with eight figures in Verhandl. d. Anat. Gesell. 
Bonn, 1901, p. 23—36. 
HoLnm6GrEN’s record of two kinds of spermatozoa in one of the 
Coleoptera suggests the inquiry, whether the second form of sperm may 
not in fact sometimes or often be functional, as well as the usual sperm. 
The order of Coleopterous insects is very large, embracing not fewer 
than 70000 species. The Insecta form an immense group, not less 
than 250000 species being known. Probably in a thousand years the 
spermatogenesis of not a tithe of either the Insecta or its order of 
Coleoptera will have been worked out. This reflection bears signi- 
ficantly upon the question of the relativity of human knowledge. 
Naturally we cannot wait another thousand years before drawing our 
conclusions: we can only say, that in our experience a second form 
is never functional, and that, though it be very often differentiated, 
there is no great likelihood of its ever being found to be of functional 
value alongside the usual form of sperm and in addition to this. 
The exceedingly interesting and important recent work of Mervss, 
referred to above, affords additional evidence of the probable truth of 
this. Meves has studied the spermatogenesis of Paludina in much 
greater detail than any preceding observer. He records, that in the 
spermatogenesis of Paludina there is no reduction of chromosomes in 
the spermatocytes of the worm-like sperm. A most curious irregular 
reduction takes place in the first of the two ensuing divisions, for 
details of which the reader may be referred to the original, and the 
