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SUMMARY 
OF CURRENT RESEARCHES RELATING TO 
ZOOLOGY AND BOTANY 
(^principally Invertehrata and Cryptoyamia'), 
MICROSCOPY, &c., 
INCLUDING ORIGINAL COMMUNICATIONS FROM FELLOWS AND OTHERS/ 
ZOOLOGY. 
A. VERTEBRATA: — Embryology, Histology, and General. 
a. Embryolog-y.f 
Theories of Heredity.:]: — Mr. E. B. Boulton gives a sketch of the 
theories of heredity propounded by Mr. Darwin and Prof. Weismann. 
He points out that the direct evidence in favour of the transmission of 
acquired characters seems to fail to stand the ordeal of a thorough 
investigation, and he urges reasons against the chief lines of indirect 
evidence. These lines are the fact of individual variation, the effects 
of use and disuse of parts, and the facts presented by the phenomena 
of instinct. The consideration of twins and monstrosities leads to the 
conclusion that individual variation is predetermined in the fertilized 
ovum. Weismann contends that the object of sexual reproduction is 
to supply variations upon which natural selection can operate. The 
apparent effects of increased use are more probably due to the opera- 
tion of natural selection upon a part which is, ex hypothesis of especial 
importance, combined with the admitted increase which follows in- 
creased use during the life of the individual. The apparent effects of 
disuse are more probably due to the cessation of natural selection, 
which can no longer maintain the efficiency of a useless part. The 
phenomena of instinct seem capable of explanation by the operation of 
natural selection upon blastogenic variations of the nervous system 
rather than by the supposed transmission of acquired habit. 
Intracellular Pangenesis.§ — Herr H. de Yries seeks to rehabilitate 
the theory of pangenesis, so far as that credits the germ-cell with an 
accumulation of minute elements corresponding to the characteristics of 
the organism. The author’s “ pangenes ” are not so small as Haeckel’s 
* The Society are not intended to be denoted by the editorial “ we,” and they do 
not hold themselves responsible for the views of the authors of the papers noted, 
nor for any claim to novelty or otherwise made by them. The object of this part of 
the Journal is to present a summary of the papers as actually published, and to 
describe and illustrate Instruments, Apparatus, &c., which are either new or have 
not been previously described in this country. 
t This section includes not only papers relating to Embryology properly so called, 
but also those dealing with Evolution, Development, and Reproduction, and allied 
subjects. X Alidland Natural., xii. (1889) pp. 245-58. 
§ ‘ Intrazellulare Pangenesis,’ Jena, 1889. Biol. Centralbl., ix. (1889) pp. 545-50 
