ON THE DEVELOPMENT OF ASCARIS NIGROVENOSA. 10] 
discoverer of the curious circumstance that that nematode 
is capable of sexual reproduction, both in the parasitic and 
its free state, in which latter condition it resembles the genus 
Rhabditis. 
This claim on the part of Herr Mecznikow has, as might 
be expected, called forth a reclamation from Professor 
Leuckart, who was thus, as it were, inferentially charged 
with having appropriated to himself in his previous communi- 
cation some of the results of his pupil’s independent re- 
searches. In a recent paper* Professor Leuckart indignantly 
repudiates this charge, and, although he allows that the par- 
ticular fact with respect to A. nigrovenosa was first noticed 
by Herr Mecznikow, this only happened in the course of an 
investigation into the life-history of the Nematoda which was 
carried on by that observer under his own immediate auspices 
and directions, and in his own laboratory and with the aid of 
his own materials. A reply to this reclamation of Professor 
Leuckart has been published in a separate form+ by Herr 
Mecznikow, and, upon consideration of the whole case, it 
appears to us that, although Professor Leuckart, might, per- 
haps, have been more liberal in his acknowledgment of the 
assistance afforded him in his researches on the subject of the 
Nematoda by his quondam pupil, still that the latter has 
claimed rather more originality than he is entitled to, seeing 
that, although he actually observed the fact of the dimorphic 
sexuality of A. nigrovenosa, he was led to this observation 
during an investigation directed in a course pointed out by his 
distinguished teacher. But leaving this very unpleasant and 
unprofitable subject, we would draw attention to some of Pro- 
fessor Leuckart’s observations upon the other contents of 
Herr Mecznikow’s highly interesting communication. 
With respect to the “cuticular lip” mentioned by Mec- 
znikow in the embryo of A. nigrovenosa, Professor Leuckart 
remarks that it is not a continuous structure or border around 
the oral orifice, but composed of three distinct papillz, as in 
all other nematode embryos hitherto observed by him. The 
rudimentary sexual organ, whose considerable size and high 
degree of development forms so characteristic a feature of 
this Ascaris-embryo, is an elongated body about 0°08 mm. 
in length, and 0°012 mm. broad, and containing, not a proto- 
plasm filled with nuclei, but distinctly isolated, though mem- 
braneless cells, 0°007 mm. to 0°008 mm. in diameter, and 
* © Archiv. f. Anat.,’ No. 6, 1865, p. 641. 
+ ‘ Entgegung auf die Erwiderung des Herrn.’ Prof. Leuckart, &c. 
Gottingen, 1866. 
