June 22, 1906.] 



SCIENCE. 



943 



chromosomes. Chromosomes are classified 

 into the following kinds : autosomes, the un- 

 modified chromosomes, and allosomes, the 

 modified chromosomes. Of the latter, two 

 kinds may be distinguished in the Hemip- 

 tera: diplosomes, those that occur in pairs 

 in the spermatogonia, and monosomes, 

 those that occur single there. The diplo- 

 somes may conjugate in the synapsis stage 

 and divide in the first maturation mitosis 

 reductionally, in the second equationally, 

 as previously described by the writer ; or 

 they may divide in the reverse order with 

 a conjugation in the second spermatocytes, 

 as described by "Wilson. Both kinds may 

 occur in the same celL The monosomes 

 usually divide equationally in the first ma- 

 turation division and do not divide in the 

 second; more rarely they divide in the re- 

 verse order; in one species the monosome 

 does not divide in either of these mitoses. 

 The same species may have two kinds of 

 monosomes as well as diplosomes. In 1901 

 the writer proved that the chromosomes oc- 

 cur in pairs in the spermatogonia, that of 

 each pair one element is of paternal and 

 one of maternal origin, and that in the 

 synapsis stage is accomplished a conjuga- 

 tion of maternal with paternal elements. 

 Here a still greater series of evidence is 

 brought in support of this contention, show-- 

 ing that for almost all the species examined 

 the determination of the pairs in the 

 spermatogonia is facile; and further, evi- 

 dence is now brought that the two chromo- 

 somes of a pair are not exactly similar in 

 volume, but apparently constantly slightly 

 different in this respect, sometimes also in 

 form, so that it is possible to distinguish 

 which is the paternal and which the ma- 

 ternal element. The simi total of the 

 chromosomes of a cell, that is, of the 

 chromatin and linin, must be regarded as 

 forming a single nuclear element, of which 

 the chromosomes, though they undoubtedly 



preserve their individuality, are only sub- 

 divisions; a particular chromosome repre- 

 sents a particular set of hereditable ener- 

 gies, the sum total of them all the energies 

 of one individual, that is to say, the sum 

 total of them when in the reduced number. 

 This state of division of labor may be 

 termed chromosome differentiation. In 

 the Hemiptera there is given the possibility 

 of following the behavior of any single 

 chromosome through a great series of cell 

 generations, as well as of deciding whether 

 it be paternal or maternal, which brings us 

 nearer the analysis of the hereditable sub- 

 stance than has been possible heretofore. 



A banquet at the Bellevue-Stratford on 

 Friday evening was the closing feature of 

 a most memorable occasion. 



SGIENTIFIG JOURNALS AND ARTICLES. 

 Dr. E. W. Taylok contributes to the June 

 issue of the Journal of Nervous and Mental 

 Disease an article on the clinical course and 

 pathological anatomy of multiple sclerosis, 

 illustrated by twelve complete case reports and 

 a number of cuts showing the microscopical 

 findings. He reaches the following conclu- 

 sions : (1) The rarity of the disease in this 

 country has been over-estimated. A more 

 careful examination of atypical cases and a 

 more open mind in diagnosis is desirable. (2) 

 The importance of observing and properly 

 estimating minor symptoms of the disease, 

 particularly unexplained spasticity and ocular 

 disorders, must be emphasized. (3) The eti- 

 ology remains obscura The pathological 

 anatomy is still a hopeful field for study. 

 Present evidence points towards a primary 

 destruction of the myeline with either a sec- 

 ondary or coincident proliferation of the 

 neuroglia. Ad. exhaustive bibliography of the 

 subject for the years since 1903 is appended. 

 Dr. G. A. Moleen repoi-ts an interesting case 

 of subcortical cerebral gumma, accurately 

 localized in the comatose state, and Dr. Alfred 

 Gordon follows with a brief contribution to 

 the study of the ' paradoxic reflex.' 



