860 REPORT— 1890. 
single-action groups there is a group of intermediate doses having the double 
action. 
13. It would appear, therefore, that four groups of gradually increasing doses 
form a cycle, which is then repeated. 
14, These results of experiments are facts. Theoretical explanations of them are 
to be rejected, such explanations being hindrances, not helps, in our search after 
truth. The facts themselves, without any explanation of them, admit of being 
made practically useful in prescribing medicines for the sick. 
For details of many of these experiments the author refers to ‘Essay LVIL., 
A Study of Doses,’ published by Messrs, George Bell and Sons, London, 1890, 
10. On the Incubation of Snakes’ Eqgs.1 By Dr. WattER SIBLEY. 
After giving a short review of the literature and referring to the observations 
of Valenciennes, Sclater, and Forbes on the increase of the temperature in the in- 
cubating female Python, the author went on to describe a series of experiments 
he had recently made on the eggs of the common English snake, in subjecting 
them to various degrees of temperature and moisture. Some eggs were placed in 
an incubator at a temperature of 90° F. and others were kept in a room of a 
temperature of 63° F., and the respective dates of hatching given. Some of the 
eggs which were kept in the room were one night placed in a low temperature of 
85° F., and many of these afterwards hatched. The author then proceeded to 
describe in detail the process of hatching. At first a slit, usually soon becoming 
V-shaped, appeared at the highest part of the egg-shell, whether the egg was 
placed on its side or on one end. At the crack the snout of the young reptile 
appeared. Then after a time the head was protruded, and often it remained out 
of the shell for some hours before the body and tail were hatched; if disturbed 
the head was again withdrawn into the shell. The author had seen the fully 
hatched young snakes return into their shells when alarmed. The appearances of 
the snakes when first hatched were finally described. They were very smooth 
and velvety to the touch, the yellow ring beautifully marked from the first, and 
the eyes open, but often there was some opacity about the cornea, which disap- 
peared in the course of a few hours. In length they were about six inches, and 
in weight about eighty grains. The characteristic hissing sound produced, when 
disturbed, was audible within the first few days. 
11. Some of the probable causes of Variation in the Eggs of Birds. 
By H. B. Hewerson. 
MONDAY, SEPTEMBER 8. 
The following Papers were read :— 
1. On the Development of the Head of the Fly of Chironomus. 
By Professor L. C. Mratn, F.L.S., and A. Hammonp. 
2. On the Structure of Muscular Fibre as demonstrated by ‘ Castings’ 
taken in Collodium. By J. B. Haycrart. 
3. Notes on the Anatomy and Morphology of the Cystidea. By P. H. 
Carpenter, F’.R.S.—See p. 821. 
1 Published in extenso in Nature, 1890. 
