159 
SPERMATOGENESIS IN IXODES RICINUS LINN. 
By ERIK NORDENSKI0LD, Stockholm. 
(With Plate XI.) 
It has long been known that ticks possess spermatozoa that differ considerably 
from the typical flagellate form. In similar cases science has always attempted 
to trace the aberrant type back to the normal with a view to identifying its 
constituent parts. Many forms, even those which at first sight appear in¬ 
capable of being compared with the normal, have recently been thoroughly 
analysed in this manner. On the other hand there occur several types of 
spermium whose parts it is impossible to compare with those of the normal 
type and in these instances all that can be done is to identify the elements 
that take part in the fertilization, viz. the nucleus and centrosome. 
Very little has previously been published on spermatogenesis in ticks. 
A. Bonnet (1907) refers to it and Samson (1909) has published a preliminary 
note on the subject whilst Robinson and Davidson (1914) refer but briefly 
thereto. None of these publications fulfils the demands of a modern investi¬ 
gation of spermatogenesis; neither as regards terminology, nor in the attempt 
to trace the development of the different elements is any attention paid to 
former scientific results on this subject. Under these circumstances it is 
scarcely possible to discuss the details of these papers; some of the stages 
described in them can by the aid of the figures be put into their proper places, 
others are impossible to identify. 
In an earlier paper (1909), I described the results of some of my researches 
on spermatogenesis in Ixodes ricinus 1 . The present paper contains several 
corrections relating to statements made in my previous communication, these 
corrections being based upon more detailed investigations that have thrown 
new light on several matters. The earlier results were obtained chiefly from 
material fixed in Carnoy’s alcohol-chloroform-acetic acid. Meanwhile it has 
been proved that this method, excellent as it is for several other purposes, is 
very unsuitable for studies on spermatogenesis. The results described in the 
present paper were obtained mainly from material fixed in Flemming’s chrom- 
osmic-acetic acid, due attention always being paid also to the Carnoy-material. 
Since my earlier paper appeared, our knowledge of spermatogenesis and 
its accompanying phenomena has considerably increased. Several matters. 
Nordenskiold (1909). Zur Spermatogenese von Ixodes reduvius. Zoologischer Anzeiger,xxxi\. 
511-516, 10 figs. ( Ixodes reduvius Latreille, 1844 = Ixodes ricinus Linn. 1758.) 
Parasitology^xii 1 \ 
