Vol. IV, No. 17. SEPTEMBER, 1908. |^JL°xVno n! 



THE ANATOMY OF THE ACRIDID^AN HEART AND 

 ITS HISTOLOGICAL STRUCTURE. 



BY LALIA V. WALLING. 

 (Contribution from the Zoological Laboratory, No. 184.) 



Submitted in partial fulfilment of the requirements for the degree of Master of Arts. 



Plate XXXVII. 



CERTAIN interesting physiological experiments on the 

 heart and respiratory activities in the grasshopper,^ led 

 to the investigations described in this paper. So many 

 of the experimental results obtained resembled those described 

 by Carlson- for Limulus, where he proved beyond a doubt the 

 neurogenic theory of heart contraction, that I hoped to show 

 the same for the grasshopper. 



On account of the small size of the heart and its delicate 

 structure this has not been an easy task. Many difficulties 

 have beset the work, and while I cannot say beyond a doubt 

 that nerve- or ganglion-cells have as yet been found, it seems 

 worth while to give some account of the methods employed 

 and the results obtained. 



This work was pursued under the direction of Dr. C. E. 

 McClung, to whom I am indebted for much valuable assist- 

 ance. I am also obliged to Doctor Hyde, at whose suggestion 

 this work was undertaken, for many helpful suggestions. 



I was able to find very little literature touching on the anat- 

 omy of the heart of any of the insects or other invertebrates, 

 and very much less concerning its histological structure. 

 DogieP described cells which he called ganglion-cells around 



1. Walling, L. v., Jour, of Exp. Zool., vol. Ill, No. 4, p. 821. 



2. Carlson, E. .7.. Amer. Jour, of Phys., vol. XII, No. 1, '04, p. 67. 



3. Dogiel, Job., Memoires de L'Academie St. Petersburg, VIT series, tome XXIV, 

 No. 10, p. 9. 



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