March 10, 1905.] 



SCIENCE. 



381 



tion of the feather elements for a given 

 ai*ea on the feather. 



New cok)r characters first appear at the 

 extreme distal end of the feather, and they 

 may move proximally, encroaching upon 

 other characters. Likewise new cliaracters 

 appear first at the distal ends of the bar- 

 bules. 



The History of the Germ-Cells in Pedicel- 

 Una americana: Louis I. Dublin, Co- 

 lumbia University. 



In this study the attempt was made to 

 work out as fully as possible the history of 

 both egg and sperm, with especial reference 

 to the chromatin, and to compare this with 

 the character of the chromosomes in the 

 various somatic tissues— thus covering the 

 entire life history of the individual. The 

 number of chromosomes is twenty-two. 

 These are, in the various somatic cells and 

 in all but the last generation of oogonia 

 and spermatogonia, distinct Vs in shape. 

 In this last generation, however, the chro- 

 mosomes are converted into rods and from 

 the size relations, it is very probable that 

 these have arisen through the extension of 

 the angle in the preceding Vs to 180°. 

 These rods split in the metaphase and pass- 

 ing to the poles give rise to eleven, or the 

 reduced number of new Vs. From the 

 rather full evidence, more particularly in 

 the sperm history, it is beyond question 

 that these new figures have arisen by the 

 end to end union of the rods at the telo- 

 phase of the last spermatogonial and 

 oogonial divisions. This is for Pedicellina 

 the true synapsis, and the conversion of the 

 chromosome form from Vs to rods is in 

 preparation for it, thus strikingly confirm- 

 ing the results of ]\Iontgomery and Sutton. 

 The eleven loops thus formed grow rapidly, 

 split longitudinally and then become ex- 

 tended into nearly straight thin parallel 

 threads, the synaptic point being at the 

 middle. The chromosomes now contract 



and form themselves into double rods, el- 

 lipses and rings, and as such enter into the 

 first maturation spindle. From the com- 

 plete history of the individual chromosomes 

 up to this point and the ease with which 

 the synaptic point may be followed this 

 division is undoubtedly the reducing one, 

 separating the chromosomes which had 

 united at the synapsis. The second divi- 

 sion is longitudinal and the maturation 

 processes are completed. 



Color Changes in Anolis: G. H. Parker 

 and S. A. Starratt, Harvard University. 

 Anolis carolinensis, according to Carl- 

 ton, changes in the dark from brown to 

 green in about twenty-five minutes, and in 

 the light from green to brown in about 

 four minutes. Temperature, however, was 

 found to influence this rate. Thus in the 

 dark at 10° C. the lizards remained brown; 

 at 20° they changed to green in about 20 

 minutes; at 25° in about 13 minutes; at 

 30° in about 11 minutes; at 35° in about 

 15 minutes; and at 40° and 45° they were 

 always green. In the light at 10° they 

 also remained brown; at 20° they turned 

 brown in a little over 4 minutes; at 25° 

 in about 3.5 minutes; at 30° in a little 

 over 3 minutes; at 35° in about 2.8 

 minutes; and at 40° and 45° they were 

 always green. Thus a low temperature 

 induces brown and a high one green and 

 both are independent of illumination. 



The changes from green to brown and 

 the reverse take place at temperatures 

 where light is an effective stimulus when 

 the lateral eyes and the pineal eye are arti- 

 ficially covered. A beam of light about a 

 millimeter in diameter and thrown upon 

 the skin is all that is necessary to induce 

 the change from green to brown. The 

 nerves of the skin of Anolis must, there- 

 fore, be sensitive to light. 



Organ-forming Sithstances in the Eggs of 

 Ascidians. Illustrated hy Photomicro- 



