: 1897 | LIFE HISTORY OF LILIUM PHILADELPHICUM 441 
no possible way of telling in such forms as Lilium what becomes 
of the individual chromosomes which go to make up the spirem 
of the reduction nucleus. The spirem is a continuous thread 
before it breaks up, and to say that each piece represents two 
of the former chromosomes is a mere assumption dangerous to 
make. It is just as probable, so far as we know, that the 
breaking may take place anywhere, and that the individuality 
of the former chromosomes is entirely lost. 
Turning now to Guignard’s + figures of the division of the 
pollen mother cells and embryo sac nucleus of LZ. Martagon, we 
find a wonderful agreement in his figures with my own. If the 
. chromosomes represented in Guignard’s figs. 48 and 49 had the 
oy chromatin band closed into a loop they would agree exactly 
With mine from this stage on. His figures indicate that the 
process of splitting was the same as I have determined, but that 
he was misled by thinking that his double chromatin band was 
Open at both ends. And were no conflicting evidence at hand 
I should say that his figures of the divisions in the pollen 
mother cells establish a transverse splitting of the chromosomes 
for the first division of the pollen mother:cells and not for the 
_ second. Whatever the fact may be, it is to be hoped that 
— evidence on this point will soon be offered which will relieve 
the present uncertainty. 
It will be seen, as already stated, that in L_ Philadelphicum, 
because of longitudinal splitting of the spirem and its subsequent 
transverse division during metakinesis, we have to do with 
_ €xactly similar phenomena as those which have been described 
_ for “tetrad” formation, although the chromosome never gives 
ay appearance of a separation into four distinct parts, but as 
_ has been described forms a double twisted coil. The early 
_ longitudinal division of the spirem, before it breaks up into the» 
Teduced number of chromosomes, has also been found by vom 
Raths in the insect Gryllotalpa vulgaris. 
_ *Nouvelles Etudes, ete. Ann. Sci. Nat. Bot. VII. rq: 163-296. r89I. 
oS Zur Kenntniss der Spermatogenese von Gryllotalpa vulgaris. Arch. fe see : 
Anat. 40: —. 1gz. - oe: é oe 
