136 CARNEGIE INSTITUTION OF WASHINGTON. 



cells and uot on the muscle. This is probably true of their action 

 in the other invertebrates. 



W. E. Castle and E. L. Mark, Museum of Comparative Zoology, 



Cambridge, Mass. Grant No. 136. For experimental shidics in 



heredity. $500- 



The work of Drs. Castle and Mark is in cooperation with the 



Station for Experimental Evolution at Cold Spring Harbor. 



Abstract of Report of W. E. Castle, 1^04. — Observations made on 

 about 3,000 guinea-pigs and 200 rabbits, whose ancestry is known 

 in most cases for several generations, indicate that : 



( 1 ) There occur in guinea-pigs at least three different pairs of 

 alternative coat-characters, which conform closely to Mendel's law of 

 heredity. These are pigmented coat, which dominates over albino 

 coat ; short or normal coat, which dominates over long or angora 

 coat, and rough or rosetted coat, which dominates over smooth coat. 

 These three pairs of characters are independent one of another in 

 transmission. Two of them occur in rabbits, as well as in guinea- 

 pigs, and are transmitted in the same manner as in guinea-pigs. 



(2) In crosses between two different types of albino rabbits, Hima- 

 layan and pure white, dominance of the Himalayan type is imper- 

 fect, but segregation of the two t3^pes in the next generation is 

 complete. 



(3) In cro.sses between lop-eared and normal rabbits an interme- 

 diate condition is obtained, which persists without segregation in 

 the next generation. In other words, this seems to be a case of 

 non-Mendelian, but of blended inheritance. 



(4) Latency is a phenomenon entirely distinct from recessiveness. 

 It is the condition of a dominant character when present unseen in 

 a recessive individual or germ. The presence of the dominant 

 character may be demonstrated by cross-breeding. 



A full discussion of these topics ma}^ be found in a paper now in 

 course of publication. Data for the study of the laws of transmis- 

 sion of several other characters have been accumulated. 



Henry E. Crampton, Columbia University, New York, N. Y. Grant 

 No. 137. For determining the laws of variation and inheritance 

 of certain lepidoptera. (For first report see Year Book No. 2, 



p. xH.) ■ $500. 



Abstract of Report. — During the year more than a thousand pupae 

 have been statistically examined, and over five hundred emerging 

 moths have been paired in order to obtain data bearing upon the 



