October 28, 1921] 



SCIENCE 



413 



and abuts against a vertical extension K of 

 the bar C. The extension K is parallel to the 

 bar J and is connected to it at its top by 

 means of a solid spring hinge. Turning screw 

 / spreads apart bars / and K and lifts the 

 whole combination (A, B and C) and imparts 

 an arc movement in the vertical plane to the 

 tip of the needle at D. To procure a vertical 

 movement the tip of the needle at D must 

 lie in the same horizontal plane L-B with the 

 spring fastening E and J together. When 

 screw I is turned the needle tip will then 

 move in an arc Y to Z more nearly vertical 

 than any other arc on the same circumference 

 of which the point D is the center. 



The rigid bar J can be attached directly to 

 the stage of the microscope, or it may consist 

 of a pillar rising from a metal base. In 

 the latter case the microscope is clamped to 

 the base alongside the pillar. In both cases 

 the needle carrier Z (Figs. 1 and 2) is ar- 

 ranged to allow the needle to project over the 

 microscope stage with its tip in the field of 

 the microscope objective. 



This instrument can be used singly for one 

 needle or with a companion when two needles 

 or a needle and a pipette are to be used si- 

 multaneously. When a pair is to be used, one 

 is a left-handed and the other a right-handed 

 instrument. 



There are two models of the micro-ma- 

 nipulator, a simple and a more elaborate form. 

 Both are identical in the accuracy and ex- 

 tent of the fine movements. The advantages 

 of the elaborate over the simple form are 

 (1) great steadiness, (2) independence of the 

 microscope from the apparatus and (3) spe- 

 cial features for the preliminary adjustments 

 of the needle or pipette. 



In the elaborate form the manipulator is 

 fastened on a pillar independent of the micro- 

 scope. The pillar is screwed into a heavy 

 base to which the microscoi)e is clamped. 

 This ensures great steadiness. The micro- 

 scope can be removed at any time, thus 

 facilitating greatly the exchange of needles 

 and the preparation of the apparatus for 

 micro-injection. Also the coarse adjustments 

 are controlled by screws which aids greatly 



in the preliminary adjustments of the needle 

 or pipette when bringing it into the focal 

 field of the microscope. 



The simple form is more compact and can 

 be clamped directly to the stage of the micro- 

 scope. Its steadiness, therefore, depends upon 

 the steadiness of the microscope stand. The 

 preliminary coarse adjustments of the needle 

 depend upon sliding movements which are 

 operated by hand. They are, therefore, less 

 readily performed than in the case of the 

 elaborate form. However, the essential fea- 

 ture of the instrument is in the fine adjust- 

 ments and these are identical in their accu- 

 racy in both forms. 



A very convenient combination is a left- 

 handed needle manipulator of the elaborate 

 type including the base and a right-handed 

 manipulator of the simple type. On the 

 other hand, the simple form either singly or 

 with both a right- and a left-handed ma- 

 nipulator, is very serviceable. 



Egbert Chambers 



Cornell Medical College, 

 New York City 



chromosome relationships in wheat 

 In 1917 the writer found the chromosome 

 number of Triticum durum to be 28 in the 

 fertilized egg cell. Since the number of chro- 

 mosomes in wheat had been previously reported 

 as 8 by a number of other investigators a sys- 

 tematic study of the chromosome number of 

 the species of wheat was undertaken, together 

 with a study of sterility in interspecific crosses 

 already in progress. This work has been in- 

 terrupted and in the meantime Sakamura"^ and 

 Kihara^ have published short accounts of the 

 chromosome numbers in wheat. Their work 

 seems to have received little attention, possibly 

 due to the lack of convincing illustrations. 



The writer has found the same chromosome 

 numbers as reported by Sakamura. Einkorn 

 has 7 haploid chromosomes ; the Emmer group, 

 consisting of T. dicoccum, T. durum, T. tur- 

 gidum and T. polonicum, has 14 haploid chro- 



' Bot. Mag. ToTcyo, Vol. 32, 1918. 

 "Bot. Mag. ToTcyo, Vol. 33, 1919, and Vol. 35, 

 1921. 



