194 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
segments of the neighbouring axial area. Variations in the pectoral 
arch and in other parts of the skeleton are associated with the pelvio 
variations. The pelvic variations were commoner in the, females. In- 
tercalation, in the sense of the introduction of new segments, does not 
take place. 
Problems of Heredity.* — Herr G. Schlater has published a lecture 
on the problems of heredity. These, he says, must first be solved in the 
domain of the single cell, wherein, like many others, he finds an array of 
structural units or cytoblasts — five different kinds in the nucleus, three 
in the body of the cell. 
There are three large questions : — The structure of the hereditary 
substance; the individuality or specific nature of this in different 
organisms ; and the mechanism of transmission. 
In discussing Weismann’s position, the author notes the difficulty 
involved in the fact that the hereditary substance in the germ-cell is to 
that in the adult (in man) as 1 : 25,000,000,000. During this increase 
there is opportunity for change or specialisation under the influence of 
the “ chief factors of development.” 
The chief factors in ontogeny include (1) the sum of external condi- 
tions ; (2) the organisation of the living matter ; and (3) the conditions of 
co-ordination and co-operation dependent on these. The chief determinant 
of inheritance is to be found in the specific individuality of the cytoblasts 
of the germ-cells. 
Experiments on Supposed Inheritance of Acquired Characters.! — 
Dr. L. Hill tested Brown-Sequard’s conclusion that, after section of the 
cervical sympathetic nerve in guinea-pigs, a droop of the upper eyelid is 
acquired, and that this droop is transmitted. In March 1895, six normal 
guinea-pigs were operated on, a droop of the eyelid was established, and 
has persisted. They were allowed to interbreed, but in none of the 
young was a persistent droop of the eyelid observable. Further ex- 
periments have proved absolutely negative. The author suggests that 
the apparent transmission of a droop in Brown-Sequard’s cases may 
have been due to individually acquired conjunctivitis, which seems 
common enough in young guinea-pigs. 
Alleged Modification of Bird's Stomach.! — Dr. G. Brandes finds a 
mare’s nest in the reputed modification of the bird’s stomach as the result of 
altered diet. His own experiments on pigeons, gulls, &c., yielded quite 
negative results. Holmgren’s were much the same, showing at most a 
general degeneration in the muscularity of the gizzard in the pigeons 
which he fed on flesh. Sir Everard Home seems to be responsible for 
the familiar results usually attributed to Hunter, who seems to have said 
little on the matter, though he made a preparation showing unusually 
strong musculature in the stomach of a gull fed for a year on corn. The 
other records are equally unsatisfactory. The nature of the stomach is 
doubtless variable, but “ there is not the slightest evidence ” of a gizzard 
being modified into a soft stomach, or conversely. Brandes suggests 
scepticism as to some other cases of alleged direct modification. 
* Biol. Centralbl., xvi. (1896) pp. 689-94, 732-41. 
t Proc. Zool. Soc. London (1896, published 1897), part 4, pp. 785-6. 
I Biol. Centralbl., xvi. (1896) pp. 825-38 (7 figs.). 
