46 SUMMARY OF CURRENT RESEARCHES RELATING TO 



y. Platyhelminthes. 



Cestoid Embryos.* — Mr. E. Linton describes and figures two forms 

 of cestoid embryo which he frequently met with in studying the entozoa 

 of marine fishes. 



The first cyst described was taken from the peritoneum of the blue- 

 fish (Pomatomus saltatrix), and similar forms are common in Teleostei, 

 occasional in Selachians. It contained an embryo Mhynchobothrium. 

 The thin, transparent, delicato outer cyst inclosed an endocyst (blastocyst 

 of Diesing). The latter was usually a club-shaped, thick-walled sac, 

 and remained active for hours with alternate contractions and expansions. 

 The embryo lay in a coil at the largo end. The water vascular canal 

 could be seen through the cyst. The wall of the cyst had two coats, 

 the outer of three layers, granular, muscular and refractile. The 

 endocyst may be regarded as an intermediate or transition form, a nurse 

 to the embryo. The freed embryo was quite active and measured about 

 24. mm. The bothria were two, marginal, oblong, divergent posteriorly, 

 notched on the posterior border, obscurely two-lobed, with free mobile 

 edges. There were four long slender proboscides armed with recurved 

 hooks. These are described in detail. The proboscis-sheaths are long 

 and spiral and exhibit a contractile ligament. The contractile bulbs 

 were thick-walled, acting like syringes, forcing a column of fluid into the 

 proboscides. The bothria are then described. The water vascular 

 system consists of a network of vessels on the borders of the bothria, 

 connected with large sinuous vessels in the centre of the head, and 

 together with these with the reticulated subcuticular vessels of the neck. 

 Behind the contractile bulbs the system is represented by two pairs of 

 lateral sinuous vessels. Behind the bulbs the body is an elongated sac 

 filled with granular parenchyma, with refractive masses smaller than 

 those of the cyst. The posterior end is terminated by a papillary 

 button-like process, retractile, and covered with dense minute bristles. 



The second cyst described was that of an embryo Tetrarhyncho- 

 bothrium, taken from the surface of the liver of the cero (Cybium regale). 

 It was long, slender, yellowish and opaque. The freed blastocyst was 

 also long and slender with a neck-like constriction at one end. The 

 head-part thus formed was extraordinarily variable. The whole body 

 exhibited irregular contractions and expansions. The embryo lay in a 

 coil in the head-part. The blastocyst remained attached to the body of 

 the liberated scolex. It would not be readily separated. The posterior 

 tapering end of the scolex was again clothed with bristles. The bothria 

 are four, in opposite lateral pairs, are quite mobile, each with a retractile 

 hooked proboscis. The proboscides were as fully developed as in the 

 Pihynchobothrium embryo. The sheaths were spirals, the contractile 

 bulbs slender. A reticulated system of vessels was made out. The 

 connection of blastocyst and scolex is a mai-ked difference at the period 

 in question between this embryo and that above described. 



Taenia nana.f — Prof. B. Grassi (with the assistance of Signor S. 

 Calandruccio) has a second preliminary note on this small human 

 Cestode. The rostellum may project, like a proboscis, very far from 

 the head, and it may be drawn very far in. In the latter state it has the 

 form of an hourglass ; it lies in a sac with a thick wall which has an 



* Amer. Naturalist, xxi. (1SS7) pp. 195-200 (1 pi,). 



t Central!)!, f. Bacteriol. u. Parasitenk., i. (1887) pp. 282-5. 



