74 MARY T. HARMAN AND FRAXK P. ROOT. 



cytes. She further states that the sex chromosomes are of the 

 XY-type which are unequal in size and separate in the first 

 spermatocyte division. Athias (1912) reports twenty-four to 

 twenty-eight primary spermatocyte chromosomes in Cavia por- 

 cellus and perhaps twenty-four secondary spermatocyte chromo- 

 somes. Lams (1913) says that there are sixteen somatic chromo- 

 somes, and eight primary and secondary spermatocyte chromo- 

 somes and eight chromosomes in the spermatids. In most cases 

 the material has been reported as very unfavorable or the count 

 doubtful. Our counts do not agree with any of those reported 

 previously. We may add, however, that in many instances our 

 material is almost diagrammatically clear. We have found 

 thirty-eight spermatogonial chromosomes and nineteen chromo- 

 somes in the primary and secondary spermatocyte cells. Like 

 Stevens, we have found an XY-chromosome which separates in 

 the first maturation division. 



MATERIAL AND METHODS. 



The present paper is limited to the number and behavior of 

 the spermatogonial and spermatocyte chromosomes. We have 

 found some interesting things in connection with the trans- 

 formation of the spermatid which we hope to give in another 

 paper. 



Two male guinea pigs were used for this study. One of these 

 animals was superactive sexually and the other was a normally 

 active male. The testes were removed and cut into small 

 sections. These were placed in cold Flemming's solution to 

 which urea had been added. This was done according to the 

 technique of Hance (1917) with the exception that the tempera- 

 ture was 2 C. instead of 4 C. The fixing fluid had been out of 

 doors several hours previous to using it. The material was 

 fixed for about twenty-four hours. The temperature was almost 

 constant during this time. The pieces of fixed testes were 

 transferred to water at room temperature for twenty-four hours. 

 The water was changed frequently. Dehydration was gradual, 

 although the drop method was not employed. Xylol was used 

 for clearing and paraffin was the embedding medium. The 

 sections were cut from three to ten mirra. Those sections from 



