130 
L. Digby 
fact that nuclei subjected to precisely the same treatment respond in 
various ways to the action of the fixing fluid, suggests the presence of 
different physiological characters. 
Further experinients have proved that the Chemical constituents of 
the special fixing niedia used produce diverse effects, as sho^vn by the 
disposition of the nuclear contents. 
The Schreiners (50) in their experinients on animal cells foimd that 
resting nuclei fixed with Hermaxx’s fluid showed a far finer chromatic 
precipitation than those fixed with acid Sublimate which caused the chro- 
matin to coalesce into larger masses. According to Rosexberg (48) ‘pro- 
chromosomes’ are far niore indefinite in preparations fixed with Fleihüixg’s 
fixing formula than with that of Carxoy. “In mehreren Fällen habe ich 
gefunden, daß Prochromosomen mit großer Deutüchkeit in Carxoy fixier- 
tem Material haben nachgewiesen werden können, während in FLEiDiixG- 
fixierten Präparaten von derselben Pflanze Prochromosomen nur mit 
Schwierigkeit sich nachweisen heßen” (p. 50). 
It has, moreover, been sho\vn that not only is the precipitation of 
chromatin affected by the constituent elements of the particular fixing 
fluid used, but also that the results are modified according to the speed 
of its Penetration. Mottier (36) in his experinients on the ovules of 
Lüium, which have already been described (see p. 126), found that direct 
Penetration caused a fine chromatic precipitation, whereas if the fluid 
had been weakened by pre\nously passing through several layers of 
cells, the chromattn was precipitated in coarser lumps. i\lEVES (32) 
observed that the chromatin of the resting nuclei of the extreme tip of 
the testis of SaJamandra maculosa was so finely precipitated as to be 
indistinguishable as such, whüst that of the nuclei of the anterior lobe 
was massed into irregulär aggregations. 
Again, nutrition plays an important part in the development of the 
nuclear chromatic contents. Overtox (40) has stated that prochromo- 
somes are only to be found in “gut ernährten ZeUkemen” (p. 124). Huie 
(23) and Eosexberg (47) have experimented on feeding Drosera with 
chemically different foods, and have obtained ^nsibie modifications in the 
nuclear contents. Huie has shown that white of egg and peptone produce 
a great increase in the chromatic sübstance, whereas such foods as nuclein 
and nucleic acid produce no such results. Rosexberg (47) has given an 
interesting series of drawings of resting nuclei taken from the tentacles of 
Drosera, demonstrating the response to the Stimulation of food as shown by 
the increase or decrease of chromatin. He believes that the size of the 
prochromosomes is alone affected and that their nuniber reniains constant. 
