16 
H. MAllSHALL WARD. 
They further point out that just as the cell- walls between 
the mother-cells of pollen are very deliquescent, so in the 
formation of the embryo-sac the dividing lamellee are swollen 
and soon absorbed in similar manner. Also the four nuclei 
arising inside each cell pollen mother-cell or constituent 
of embryo-sac) are arranged in tetrahedra in either case. 
If this account be accepted, the eight nuclei are homologous 
with pollen grains, i.e. spores, and the egg-cell is not 
to be regarded as the hornologue of the “ oosphere ” of vas- 
cular Cryptogams, but as a macrospore which never germi- 
nates ; and may be regarded as containing in itself the 
representative of the whole prothallus and archegonium. 
But a careful survey of the facts in many different types has 
convinced Strasburger that no such fusion of two mother- 
cells occurs, and we see no such process in Gymnadenia as 
Vesque describes in Orchis galatea / especially does he appear 
to overlook the gradual compression and absorption of the two 
upper (cap) cells. The analogy between the mode of divi- 
sion in the embryo-sac mother-cell and the primitive cells of 
pollen-forming layers in an anther can probably be ex- 
plained in a totally different manner,^ and in any case we 
can lay no stress on it so long as it is unsupported by other 
evidence. 
The following argument against this view appears to me 
important, especially if we take into consideration the many 
analogies tending to the conclusion that the Angiosperms 
are a series in which the reduction of the prothallus 
generation ” (oophore) is reaching its limit. 
The pollen grain has been found to contain two nuclei,^ ap- 
parently representing incipient germination changes — the 
first division in the microspore to form rudimentary pro- 
thallial structures. This being the case, from analogy with 
Cryptogams and Conifers (where we find it is always the 
microspore and male prothallus, &c., which suffer reduction 
first) we may argue the probability that whatever represents 
the macrospore will not have undergone more suppression 
than the microspore, and probably much less. But I think 
there is another reason for not imagining the female pro- 
thallus to be entirely atrophied, and for holding that the 
stages of reduction past a rudimentary archegonium art 
* Loc. cit. Vesque’s account of the facts also differs from that oii 
here. 
2 See an attempt in paper to Linnsean Society, read Nov. 20th, 1879, 
“ Contributions to Knowledge of Embryo-sac,” &c. 
* Strasburger, loc. cit., and Elfving in ‘ Jenaische Zeitschrift,’ B. xiii. 
See the account of Elfving’s researches in the present number of this 
journal. 
