160 NATURAL SCIENCE _ - [September 1898 
should have an opposite pair of seed-leaves. Gaertner, who first drew 
attention to this seedling, considered that the first leaf, to which we 
have referred, and which grows to a large foliage leaf, is the only 
cotyledon. Other botanists have taken the same view, while some 
maintain that a second cotyledon is developed later. Dr Hildebrand 
does not consider the nomenclature of these early-developed leaves a 
matter of importance, but carefully describes what happens. The 
development of the second leaf, presumably the second cotyledon, may 
be accelerated by removing the first. The author has had the inesti- 
mable advantage of observing the life-history of the species from seed 
to seed, and has been able to make many useful observations which 
would have been impossible if dried material only had been avail- 
able. Among others we note an interesting correlation between the 
duration, or time of appearing, of the leaves and the length of the 
dormant period before the expiration of which this seed will not 
germinate. ; 
The section on variation should be read by all who are interested 
in this subject, as bearing on the relation between variation and a 
changing environment. 
The value of Dr Hildebrand’s memoir is enhanced ‘by half-a- 
dozen clear, double-paged plates, containing numerous figures. 
THE FEMALE OF HETEROGYNA 
THE recently published part 2 of the Transactions of the Entomo- 
logical Society for the current year contains (pp. 141-150) another 
of Dr T. A. Chapman’s valuable papers on the life-history of Lepi- 
doptera. He describes the transformations of the South European 
Heterogyna penella—a small dusky moth with wingless female, often 
associated with the Psychidae which it resembles, but from its early 
stages apparently nearer to the Zygaenidae. The vermiform female 
imago remains attached to the ventral face of the pupa skin. She 
emerges from her cocoon for pairing, but withdraws into it again 
after fertilization, becoming replaced exactly in her former position 
in the pupa as before emergence. Oviposition then begins, and the 
pupa skin becomes largely filled with eggs, the shrivelled body ot 
the female stopping up the aperture and protecting the eggs against 
drying up, as well as against insect parasites. Dr Chapman believes 
that the object of the return of the female into the pupa skin is to 
ensure this protection for the eggs. And maternal self-sacrifice is 
carried yet further, for the young caterpillars’ first meal is on the 
remains of their parent. This concluded, they bore through the 
pupa skin and take to their food-plant. 
