and Fertilization in Oenothera. 
2 97 
hypotheses as yet proposed. Really, triploid mutants in Oenothera were 
reported by Lutz (38), Stomps (63, 64), and Gates (19$). The first-named 
observer, having found them in the offspring of Oenothera lata x Oe. 
Lamarckiana and self-pollinated Oe. lata , attributed the origin of such 
mutants to the union of the reduced male nucleus and unreduced egg 
nucleus. Stomps independently published the occurrence of a similar 
phenomenon in Oe. Lamar ckiana, which he named semigigas, and he got 
also a triploid offspring from Oenothera biennis and named it Oenothera 
biennis semigigas. Though these first two investigators did not touch the 
dispermic problem, the case would be easily and smoothly explained by 
Nemec’s hypothesis, which has, however, been suggested by Gates as being 
less probable than the union of diploid and haploid sex nuclei . 1 
After the ejection of the contents, the opening at the tip of the pollen- 
tube is closed by some mucilaginous substance (PI. VII, Fig. 8 ; Text- 
fig. VII, i, 3 , m.s.) forming the residue (r.s.) of the contents of the tube. If 
there remain any starch grains they gradually disappear, and the contents 
finally become filled with many globular liquid drops as shown in Text- 
fig. VII, a, r.s. The filiform apparatus persists for a long time, even when 
the rest of the synergids is entirely absorbed at the time of embryo 
formation. 
Cell Walls of Egg Apparatus. 
For the determination of the chemical character of the cell walls 
of the egg apparatus, a great many microtome sections have been treated 
with different stains and reagents, and the results obtained are as follows : 
Filiform apparatus. The filiform apparatus (Text-fig. VII, i and 
was stained red with aqueous solution of Congo red ; also it was coloured 
purplish blue with chlorzinc-iodine. A treatment with freshly made cupram- 
monia gave the following result. Sections were allowed to stand in this 
reagent for half a day to 30 hours; the apparatus was then found entirely 
dissolved, as shown in Text-fig. VII, 4 , ap., often leaving some cloudy residue. 
1 After the manuscript was finished, Dr. I. 6sawa published an interesting account of triploid 
mutants in the garden races of Morus in the Bulletin of the Imperial Sericultural Experiment Station, 
Japan, vol. i, No. 4, 1916 (Japanese). According to this investigator, in forty-two garden races of 
Morus examined by him, supposed to have been derived from Morus bombycis , M. alba , M. indica , 
and M. multicaulis (?), each of thirty-two races possesses fourteen haploid and twenty-eight diploid 
chromosomes. And a certain one of the fourteen haploid chromosomes is very conspicuous for its 
remarkable size. On the other hand, in the remaining ten races he studied, forty-two chromosomes 
are equally found in the vegetative cell, three of which are always markedly larger than the 
others. As he did not find such a race that has twenty-eight haploid chromosomes, he is inclined to 
believe that those ten races just mentioned have not been derived from a hybrid between two kinds of 
races which possess fourteen and twenty-eight chromosomes respectively, but really descended from 
a triploid mutant. Although the investigator adopts the prevailing hypothesis, i. e. the union of the 
haploid and diploid generative cells for the explanation of the origin of those triploid mutants, the 
case will be smoothly explained by Nemec’s hypothesis. The triploid mutants in question are all 
sterile, as Dr. Osawa stated, but having been propagated vegetatively, for instance by grafting, so 
many triploid mutants seem to have been preserved and protected from extinction. 
