Reduction in Animals and Plants. 
433 
distributed equally amongst the two daughter-nuclei as in 
ordinary nuclear division, but in one half of the entire number 
of rods passing into one daughter-nucleus, and the other half 
into the other.’ 
In 1890 O. Hertwig 1 described the last mitosis in the 
spermatogenesis of A scar is as possessed of this peculiar 
character, and the announcement was at once greeted by 
the supporters of Weismann’s theory, as a demonstration 
of their leader’s views. ‘ Reductionstheilungen ’ were im- 
mediately described in many forms, and Ischikawa 2 was so 
much impressed with the similarity between the last spermato- 
and oogenetic divisions in Diaptomus and those described by 
Hertwig, as to say when speaking of the latter’s paper, ‘ In 
this work is given for the first time a clear insight into the 
exact parallelism existing between the egg and sperm-cells — 
every point in which corresponds so exactly with the descrip- 
tions given in this paper, that it seems almost superfluous to 
have published them.’ 
But in spite of this, the difficulties of getting the original 
conception of the process to fit in with spermato- and oo- 
genesis (like that of Branchipus described by Brauer 3 for 
example), have evidently led Dr. Haecker to have recourse 
to the ‘schema’ given on page 98, and to hypothetical 
arrangements of the chromosomes, by which (if they exist) 
something equivalent to a ‘ Reductionstheilung’ may occur. 
All this is an ingenious piece of dialectic fencing, but at 
the same time quite sufficient in itself to show that the 
Reductionstheilung as a base on which to build a theory of 
heredity is not likely to be worth much now. 
In 1893, however, Brauer 4 published another and more 
elaborate account of the spermatogenesis of Ascaris , which 
1 Vergleich der Ei- und Samenbildung bei Nematoden, Arch, fur Mikr. Anat., 
Bd. XXVI, 1890, p. 1. 
2 Spermatogenesis, oogenesis, and fertilization in Diaptomus , Journ. Sc. Coll. 
Tokayo, Vol. v, p. 22. 
3 Uber das Ei von Branchipus Gmeli var. Dyb. von der Bildung bis zur Ablage, 
Anhang z. d. Abhandl. d. Kgl. Preuss. Acad. d. Wissensch. Berlin, 1892. 
1 Arch. fiir. Mikr. Anat., Vol. xlii, 1893, p. 153. 
