PACKARD. — INHERITANCE OF ACQUIRED CHARACTERS. 343 



but primary, dating from the time when the embryo was a unicellular 

 structure. . . . My own investigations ou tbis subject have been con- 

 fined to the Artbropoda, Elasmobrauchii, and Aves. I have thorougbly 

 examined the development of at least one kind of each of these groups, 

 and I have never been able to detect a stage in which the cells were 

 not continuous with each other ; and I have studied innumerable 

 stages from the beginning of cleavage onwards.'" 



As regards plants, De Vries * and other botanists believe that all 

 or the greater number of cells in the plant body contain the total 

 heredity characters of the species in a latent condition. f 



In this connection should be noted an observation of Maupas, who 

 saw the cytoplasm of an infusorian pouring into the nucleus until its 

 bulk was increased eight times. 



Hoffman observed the transmission of acquired characters in the 

 poppy, etc., as the result of deficient nutrition. | 



In 1890 Van Bemmeliu § gave a useful and very exhaustive account 

 of the doctrine of heredity, with especial reference to the question of 

 heredity of acquired characters, stating the views of various patholo- 

 gists, anthropologists, and physiologists. In conclusion he makes some 

 objections to the view that the germ plasm is independent of external 

 influences. 



I am indebted to Prof. G. W. Field for the statement that MM. 

 Charrin and Phisalix || cultivated Bacillus pyrocyaneus for several 

 successive generations at 42.5° C. with the result that it lost its 

 chromogenic property. This non-chromogenic character apparently 

 thus acquired was retained upon cultivation under most favorable cir- 

 cumstances, and it seemed to show no tendency to recover the chromo- 

 genic property. 



"Laurent modified the chromogenic function of the Kiel water 

 bacillus by exposing it to direct sunlight for a limited time. The 

 suppression of this peculiarity was transmitted from generation to 

 generation, so that a perfect albinotic variety was formed. The color 

 property was also lost when cultivated at blood heat, and was not 



* Intracelliilare Pangenesis, Jena, 1889. 



t Osborn, loc. cit., p. 62. 



t Biol. Centralblatt, 1887, p. 667; Botan. Zeitung, 1887, pp. 260, 772, 773. 



§ De Erfelijkheid van verworven Eigenschappen. 's Gravenhage. p. 279. 

 (See abstract by V. Haecker in Biolog. Centralblatt, Bd. X. pp. 641-652, 686- 

 694. Also a brief abstract in Zoologischer Jahresbericht fur 1890, Alg. Biologie 

 u. Entwick., p. 23.) 



|| See Comptes Rendus, 1892, CXIV. 1565-1508. 



