192 Farmer and Digby.—On the Cytological Features exhibited by 
to this extent limits the possible directions of the course of metabolism 
which ultimately finds expression in structure and form, it is the nucleus 
which determines and controls the line which is actually followed. 
We think the highly important and interesting experiments of 
C. Herbst 1 2 3 strengthen this view. Herbst found that by starting the 
development of an ovum on parthenogenetic lines he was able to influence 
the character of the offspring in the maternal direction—and he has more 
recently - succeeded in correlating this with the cytological facts— and to 
show, though indirectly, how large a share the nucleus takes in determining 
the nature of the individual to which such an ovum will give rise. 
It is evident that questions such as these can only be answered by 
extending the scope of investigation. Whilst the method of direct experi¬ 
ment will ultimately bring us nearest to the goal, the less direct method of 
observation of those disturbances which often follow on a less artificial 
deviation from natural conditions cannot fail to be profitable. Hybrids 
have already yielded results of importance, and recalling the opportunity 
which presented itself some years ago of investigating a hybrid fern, Poly¬ 
podium Schneideri;' we determined to inquire into the cytological features 
attendant on the development of the spores. We hoped that some definite 
information might thus be obtained which would throw light on certain con¬ 
troversial points connected with meiosis, and especially the prophase stages 
of the heterotype mitosis. Although the fern has not fulfilled our expecta¬ 
tions in this respect, owing mainly to the small size and the large number 
of the chromosomes, it has nevertheless yielded other results which appear to 
us to be of sufficient interest to be worth recording. 
P'olypodium Schneideri was raised by Mr. Schneider in the nurseries of 
Messrs. Veitch and Sons, Chelsea. It was stated to be a cross between 
P. aureum and P. vulgare var. elegantissimum , the latter a beautiful laciniate 
variety of the common polypody which was found in the wild state. In its 
general external and anatomical features the hybrid bears out the state¬ 
ments made as to its parentage, and the existence of leaves on which pinnae 
that have ‘ reverted ’ to the simple form of the type in each parent lend 
further support to the claims made on its behalf. These £ reverted ’ pinnae 
sometimes possess the character of a coarse polypody leaflet, but occasionally 
they also have the glaucous colour and bloom of the other parent. There 
is at the present time growing at the Chelsea Physic Garden (where our 
material has all been cultivated) a plant showing a fine instance of such 
a £ reversion ’ in some of its lower pinnae. 
Sporangia are produced fairly freely on both the ordinary and the 
£ reverted ’ fronds, but in no case have we ever found the spores to be 
1 C. Herbst, Vererbungsstudien, IV. Arch, f. Entwick.-mechanik, Bd. xxii. 
2 C. Herbst, Vererbungsstudien, VI. Arch. f. Entwick.-mechanik, Bd. xxvii. 
3 Farmer, J. B., On the structure of a Hybrid Fern. Ann. Bot., xi. 
