

LIVING BRACIIIOPODA. 359 



the dorsal side of the stomach, or anywhere along' on the digestive tract, or anywhere else 

 in the anatomy. Glandular conditions arise on the edge of the gastro- and ilio-parietal 

 bauds as well as upon the mesenteries during genital activity and if this growth takes 

 place on the dorsal mesentery, it might easily be mistaken for the so-called heart. I have 

 examined with the greatest care many living Terebratnlina and numbers of the large 

 Terebratalia corvuiilcn, Dnffhin t/rin/ii, and ff&nithyris psittctcea, solely for the purpose 

 of studying this problem. I have opened individuals quickly, yet with great care, and 

 have never seen the slightest signs of contractility or change of form either in the central 

 or accessory organs denominated as hearts, nor could these vesicles be made to contract 

 by the application of external stimuli, such as pricking with a needle. This is all the 

 more singular, since all other parts of the organism are in constant movement. No 

 matter how rudely the shells were torn apart (and in this operation almost the only parts 

 that were not ruptured by this mutilation were the intestine and the dorsal vesicle) the 

 various movements of the parts have continued for hours after this rough treatment. 

 The various lobules of the stomachal glands are incessantly expanding and contracting, 

 the stomach and oesophagus exhibit peristaltic and other movements hours after excision, 

 the lips of the mouth and the delicate brachial fold at the base of the cirri continue to 

 bend and wave, the cirri are continually turning and swaying in various directions, the 

 circulation of blood goes on actively in the sinuses and lacunae of the pallium and in 

 other parts, and an equally active circulation is seen in the tubular cavity of the 

 peduncle, even days after its separation from the body black with decay, and yet the 

 so-called heart gives no sign of contraction. It may be said without exaggeration that 

 the only part of the anatomy which manifests no movement, which is absolutely inert, is 

 the so-called heart. As to the well defined veins which Hancock describes in the pallia! 

 sinuses and lacunae, we have seen that they are ciliary ridges which continue into the 

 minutest ramifications. 



In any discussion as to whether the " heart of Hancock " is really a propellent organ 

 and implicated in the circulation of the blood, two matters must be considered : first, 

 that the Brachiopoda are remarkably alike iu all leading structural details, and for this 

 reason it is difficult to conceive of so fundamental a structure as a pulsating heart being 

 present in one group and not even a vestige of it to be found in another group ; second, 

 one has only to realize the active and abundant flow of blood in the perivisceral and 

 pallial circulation, to be convinced of the utterly inadequate character of the little 

 pyriform vesicle to induce such a flow, and when one turns to Glottidia and Lingula and 

 witnesses the voluminous and impetuous flow of blood through the sinuses and yet finds 

 no trace of a heart or a pulsating organ to induce this current, he is compelled to find 

 some other explanation for the function of this vesicle in the Testicardines. 



