and Laboratory Methods. 2713 



changes in the volume of the heart may be measured. This whole portion of 

 the apparatus lies in a larger glass vessel (g), through which water of a constant 

 temperature may be circulated, when it is desired to study the effects of different 

 temperatures on the heart's action. The vessel (e) serves as a blood reservoir 

 from which the heart takes oxygenated blood through the venous tube e//i. The 

 blood reservoir is again placed in a larger vessel (d) in order that the temper- 

 ature may be controlled. Through the cannula /the blood is brought into the 

 sinus venosus, while the cannula /' conducts it from the left aorta out into the 

 arterial glass tube k m. This arterial tube has at / a T-cock and a branch tube 

 leading off to the manometer tube n. By means of this manometer the blood 

 pressure at each stroke of the heart may be measured. The arterial tube proper 

 ends at m, and from this opening the blood drops freely back into the blood 

 reservoir (e). This opening m stands 11cm. above the heart, while the reservoir 

 (e) can be raised or lowered as desired. The venous tube from o to i-is made of 

 rubber tubing so that the amount of blood passing to the heart may be controlled. 

 The reservoir may, of course, be filled with any nutrient fiuid whose action on the 

 heart it is desired to test. The author finds that the best results are obtained 

 with defibrinated arterial blood. The apparatus serves admirably for the dem- 

 onstration of the phenomena of the circulation, as well as for investigations on 

 the heart. r. p. 



Holmes, S. J. Sex Recognition among Am- Certain of the amphipod Crustacea 

 phipods. Biol. Bull. 5: 288-202, iQC?. , 1 r n • ■ 1 i_-^ 



^ ^ ^ J have the following curious habit con- 



nected with reproduction ; for some time before the eggs are laid the male tightly 

 clasps the female and carries her about with him. The purpose of the habit is 

 probably merely to ensure the close proximity of the sexes at the time of egg 

 laying in order that the eggs may be properly fertilized. The problem to which 

 Holmes has addressed himself is this ; how do the males recognize the females ? 

 The account given is based on the reactions of HyaUella. It is found that dur- 

 ing the period of clasping the female is remarkably impassive, keeping the body 

 as compactly drawn together as possible, and taking little or no part in the 

 swimming. The female as soon as seized by the male curls up and allows her- 

 self to be rolled about without a show of resistance or protest. By blackening 

 the eyes of some males it was shown that sight plays no part in sex recognition, 

 as these blinded males were soon provided with mates. That the sense of smell 

 is not an important factor in this recognition was shown in two ways. In one 

 experiment the first antennae, in which the sense of smell is localized, were 

 removed from several males, and these mutilated individuals were then put into 

 a dish with females. In all cases the males seized the females and carried them 

 about just as normal males would have done. In another experiment the males 

 and females in the same dish were separated by a wire gauze partition. Under 

 these conditions the males paid no attention to the females, although as soon as 

 the partition was removed the males quickly acquired partners. It was found 

 by close observation of normal animals that the males do not pursue the females, 

 and that the determining factor in sex recognition is found in the reactions of 

 the individuals when they accidentally collide in swimming about. If a male 



