112 BULLETIN OF THE 



uiul eincs spiiter auftretenden oralcu Schlanchcs, an dercn Cildiuig 

 freilich das iiussere Kuosj)eublatt nur secuudiir sich betheiligt, zu Staude 

 komnit." 



]\Iy own observations are nearly in accord with tlie statements of 

 Braem, as opposed to Nitsche's. Tiic older bud of FiL,''iire 11 (Plate II.) 

 shows the lirst indication of the lunicn of the posterior part of the ali- 

 mentary tract near the attached portion of the Imd. The cells of the 

 inner layer are inultii)lvini:- and the lumen of tlic bud is broader hero 

 than elsewhere. The position of a daughter bud, VI. (on the oral side of 

 the one under consideration), sufficiently indicates tliat the point marked 

 r(. is in the region of the future anal opening. Figures 12 and 13 (Plate 

 II.) show further stages in this same process. The lumen of the intestine 

 is formed, not by constricting off a part of the original lumen of the bud, 

 but by the rearrangement of cells at the progressing blind end of tlie 

 pocket, which gradually moves towards the distal part of the larger or 

 bud cavity. It is important to establish the fact that the alimentary 

 tract is formed in tlie inner layer of the bud, and that its cells alone line 

 the digestive cavity. Figures 20 and 21 (Plate III.) repi-esent two suc- 

 cessive sections out of live which pass through the imier layer ; namely, 

 the second and the tliird counting from the attached to the free end of 

 the bud. Tlie sections were cut at right angles to the plane of Figure 

 11 nearly along the lines 20 and 21 respectively. It will be seen that 

 the inner layer alone is implicated in the lining of the alimentary pocket 

 at this earlv acre. Thev also show clearlv the incorrectness of the state- 

 ments of Nitsche on this j)oint. Figures 24, 25, and 2G (Plate IV.) are 

 three sections cut through a bud of about the age of that represented in 

 Figure l."3 (Plate II.), and at right angles to the plane of the latter, and 

 in the direction of the lines 24, 25, and 20 respectively. A section cut 

 bevond the end of the intestine, in Figure 13, is not represented. It 

 shows th:it the lumen of the alimentary tract is absent at this plane. A 

 comparison of Figures 20 (Plate III.) and 2G (Plate IV.) shows that the 

 lumen of the bud, la.r/m. (which we may call the atrium from its resem- 

 blance to a space having the same relations in Fntoprocta), has increased 

 in volume owing to a growth of the lateral walls. C>!! account of the 

 mere i-apid elongation of the anal than of the oral side, the axis of the 

 alimcntarv tracts comes to take a horizontal position, as shown in Fig- 

 ures 17 and 18, Plate HI. (Compare also Figs. 27-20, Plate lA^) The 

 blind end of the digestive sac comes very close to the blind end of 

 another pocket formed on the oral side, the osdphagus, and soon the 

 two communicate directlv. At the same time, the inner cell-layer of the 



