SUMMARY OF CURRENT RESEARCHES RELATING TO 



carefully investigating their structure and history. The character of 

 the stomatodendra is still almost unknown ; it is still believed by 

 many that they have the function of suckers, a view which is not 

 supported by the facts. 



In Archirhiza primordialis, the eight stomatodendra are unjointed 

 and unbranched ; and through them there passes a canal or vessel, 

 the primary canal. On their axial side they are provided with 

 suckers, which may henceforward be known as infundibular frills 

 and their orifices as the infundibular orifices ; each frill has always 

 the shape of a funnel, and in each there is a canal, derived from 

 a primary vessel of the arm. In Cepliea conifera the primary canal 

 divides into two secondary ones, which again give off smaller 

 branches. In Polyrhiza vesiculosa the stomatodendra branch dicho- 

 tomously, but the vascular system resembles that of the preced- 

 ing form. In Cassiopeia ornata, the eight cylindrical arms break 

 up into three or four pairs of primary branches, which again divide ; 

 here there is such an alteration in the vascular system that the canals 

 are branched. After dealing with these forms of the Toreumidee, the 

 author passes to the Pilemidae, where he finds a primary vessel with 

 three subsidiary ones, which run parallel to it. In the Versuridte the 

 frills are confined to the ventral surface of the stomatodendra, and the 

 vascular system is consequently simple. In the Crambessidse there is 

 a primary vessel in the upper arm, which, at the base of the pyra- 

 midal lower arm, divides into three subsidiary branches, which give 

 vessels to the three rows of frills. 



In discussing the origin and structure of the digitelli, or small tenta- 

 cular organs which are found around the orifice of the infundibular 

 frills, the author states that there is always found in them, just as in the 

 gastric filaments, an axis of gelatinous substances, invested by a layer of 

 ectodermal epithelio-muscular cells ; the axis appears to be broken up 

 by transverse constrictions into chorda-like cells, but this is a pheno- 

 menon which is only apparent after the death of the animal. They 

 are to be distinguished (1) from the true tentacles by the fact that 

 these, which primitively arise from the margin of the disk, have their 

 axes hollow, or formed by endodermal cells, and (2) from the gastric 

 filaments, which have their axes invested by endodermal epithelium. 



In attempting to solve the problem of how the four mouth-arms of 

 Aurelia (e. g.) became the eight stomatodendra of Mliizostoma, the author 

 appeals to the Aurosa furcata of Haeckel, where the four arms are each 

 divided by a notch into two diverging pieces ; the canal appears, in 

 development, to divide first, and he thinks that the form of the 

 lobes is but a secondary process. After treating of some other 

 parts connected with these organs, the author examines the question 

 of the mode of nutrition ; he finds that in hungry specimens the in- 

 fundibular frills with their orifices ai'e widely open. When an animal 

 adapted for prey comes near the orifice, the frill, owing to its posses- 

 sion of epithelio-muscular cells, is able to extend itself, and by means 

 of the digitelli to seize the creature. Within the frill, the captm-ed 

 animal is digested by the endodermal investment, and frills have been 

 found containing the half-digested remains of Crustacea. The nutri- 



