February 7, 1902.] 



SCIENCE. 



229 



'The trend of insect migration in America': 

 F. M. Webster. Read by title. 



'A Plasmodium found in the blood of a turtle 

 and related to the plasmodium of malaria': C. B. 

 MOBEET. Presented by Herbert Osborn. 



E. L. MOSELEY, 



Secretary. 



NEW YORK ACADEMY OF SCIENCES. 

 SECTION OF BIOLOGY. 



A KEGULAE meeting of the Section of Biol- 

 ogy was held on January 13, Professor Charles 

 L. Bristol occupying the chair. The following 

 program was presented: 



1. 'The Relation between the Variability of 

 Oells and that of Organisms': Franz Boas. 



2. 'Degeneration in Paramoecium and so- 

 called Rejuvenescence without Conjugation': 

 Gary N. Calkins. 



3. 'Natural Selection in Samia cecropia' : 

 Henry E. Crampton. 



Professor Boas, in his paper, which has 

 been printed in full in Science for January 3, 

 1902, established the following conclusions : 

 " (1) The elements of organisms are more 

 variable than the organisms themselves. 

 (2) The elements of organisms vary in cor- 

 related groups. (3) The characteristics of the 

 variability of an organism depend upon the 

 correlations of its constituent elements, so that 

 a knowledge of these correlations wiU enable 

 us to determine the characteristics of the vari- 

 ability of the organism." (4) It was also 

 pointed out that skew distribution of varia- 

 tions does not necessarily indicate selection, 

 or instability of type, but may occur in stable 

 forms. 



Dr. Calkins presented the history of two 

 individuals, A and B, of Paramoecium cauda- 

 tum, from different localities, which were iso- 

 lated February 1, 1901. These were fed on 

 twenty-four hour hay-infusion, and the num- 

 ber of divisions recorded at periods of from 

 one to three days throughout the year, one 

 individual being isolated each time. Conjuga- 

 tion occurred for the first time, among the ex- 

 tras, in May. This period was followed, in 

 July, by well-marked degeneration of both A 

 and B, which went so far that nearly all of 

 the stock was lost. The survivors were stimu- 



lated to renewed activity by treatment with 

 extract of lean beef. After three months of 

 normal and active divisions, another period of 

 conjugation occurred. This again was fol- 

 lowed by degeneration and again the cultures 

 were saved by treatment with beef -extract. At 

 the present date (January 13), A is in the 

 416th generation, and B in the 375th genera- 

 tion, and no conjugation has taken place in 

 the direct line of the cultures. Thus far the 

 experiments have yielded the following re- 

 sults : (1) Paj'amcBciwm unquestionably passes 

 through more or less regular cycles of activ- 

 ity and weakness. (2) The period of weakness 

 is preceded by one of greater dividing activity. 

 (3) The period of weakness ends in death, pro- 

 vided the diet (hay-infusion) remains the 

 same. (4) Beef-extract, without conjugation, 

 restores the weakened functions of growth and 

 division. (5) Exogamous conjugation of A and 

 Bj if followed by the same diet (hay-infusion) , 

 does not restore these weakened activities, but 

 is soon followed by death. (6) Exogamous con- 

 jugation between wild gametes, and followed 

 by hay-infusion diet, results in normal growth, 

 division, and life. (7) Endogamous conjuga- 

 tion among gametes from the cultures 

 does not differ from exogamous conjuga- 

 tion. The ex-conjugants live and divide nor- 

 mally if fed for a time with beef-extract, but 

 die if fed directly with hay-infusion. (8) One 

 intra-cellular effect of beef -extract upon weak- 

 ened Paramoecium is the formation of 'excre- 

 tory granules.' Another is the disintegration 

 of the old maeronueleus. (9) A few conclu- 

 sions to be drawn are : (a) a change of diet 

 is necessary for the continuance of vital ac- 

 tivities; (&) the equivalent of parthenogenesis 

 in higher animals may be induced by change 

 in diet; (c) conjugation, by itself, does not 

 'rejuvenate'; (d) conjugation probably has 

 some other significance than that usually ac- 

 cepted, though what this significance may be 

 is not indicated, thus far, by the experiments. 

 Professor Crampton presented the results of 

 a statistical study upon pupae of Samia cecro- 

 pia. Twenty-five characters were determined 

 for a lot of 456 pupae, the measurements were 

 tabulated, and the usual constants of the 

 curves of variation were ascertained, viz., the 



