652 SUMMARY OF CURRENT RESEARCHES RELATING TO 



pole of the egg seems less encumbered with yolk ; the blastoderm at least 

 is so elevated that processes going on in it are quite as independent as in 

 the amphibian egg. Among other points of interest, it may be noted 

 that there is practically no evidence in Phrynosoma that either the 

 chorda or hypoblast contributes anything toward the origin of the 

 mesoblast. 



Terminology of Organs in Various Conditions of Development.* 

 J. H. Schaffner has made a useful attempt towards greater precision 

 of terminology. An " incipient " organ is one in its first stages of 

 development in the life of the individual, and " incept " is proposed as a 

 synonym for primordium or anlage. A " nascent " organ is one at the 

 beginning of its evolution. A " vestigial " organ is one which was 

 normally developed in the past history of the race, but wbich has 

 become permanently reduced, never developing completely in an 

 individual. An " abortive " organ is one normal in the species, but 

 which has failed to reach full development in the individual. An 

 " atrophied " organ is one which is normal in the species and fully 

 developed in the individual, but which has become reduced through 

 pathological conditions or through disuse. Imperfectly developed or 

 reduced organs of all types may be called rudimentary. A " rudimentary " 

 organ is one in an initial, incipient, or incomplete state of development ; 

 or one that has become reduced either in the history of the race or of 

 the individual. " Atavistic " organs are such as show in the individual 

 a return to some ancestral type. " Retrogressive " organs are such 

 as are passing from a higher to a lower or less perfectly developed 

 condition or state of organisation. "Abnormal" organs are those 

 which deviate from the usual type in some extraordinary way. A 

 " malformed " organ is an unusual growth due directly to some external 

 condition in the life of the individual. " Transformed " organs are 

 such as show a change in the individual or the race from one type of 

 structure or function to another. " Insect wings are probably trans- 

 formed gills," the author says. " Juvenile " organs appear in the young, 

 but are absent in the adult. 



Movements of Snake Spermatozoa.! — H. Adolphi, continuing his 

 observations on the movements of spermatozoa, finds that in the adder, 

 as in many other forms, the spermatozoa swim against a current. Rates 

 of 50-80 p per second were observed. The habit of moving against 

 currents doubtless helps in the ascent of the oviduct. 



Development of the Retina in the Salmon. J — C. M. Furst dis- 

 tinguishes three chapters in the development of the retina. (1) The 

 cylindrical epithelium stage ; (2) the differentiation stage ; and (8) the 

 growth stages in which the rods and cones are formed. Each of these 

 stages is described in detail. The first stage is marked by cell-multiplica- 

 tion ; the second by the integration and displacement of cells ; the third 

 by the growing out of the terminal organs of the visual cells (rods and 

 cones), and by changes in the shape and size of all the retinal cells. 



* Ohio Naturalist, vi. (1906) pp. 541-4. 



t Anat. Anzeig., xxix. (1906) pp. 148-51. 



X Acta Univ. Lund., xl. (1904, received 1906) pp. 1-45 (2 pis.). 



