X CONTENTS. 



Chapter XXXV. TUNICATA— continued. pa<*e 



. 355 



. 357 



. 360 



. 361 



. 362 



. 364 



. 366 



The mantle 



The nervous system .... 



The ciliated pit 



The chorda ...... 



Mesoderm, body-cavity, musculature . 

 The alimentary canal .... 



Peribranchial, atrial or cloacal cavity . 



The heart, the pericardium and the epicardium . . 368 



E. Review of the organisation of the free-swimming larva . 371 



F. Fixation and retrogressive metamorphosis . . . 372 



The development of new gill-slits .... 376 



The development of the genital organs . . 379 



<r. The abbreviated development of the Molgulidae . . 381 



3. Doliolum 382 



4. Pyrosoma ........••• 389 



A. Cleavage and formation of the germ-layers . . . 389 



B. Development of the Cyathozooid 393 



G. Development of the primary Tetrazooid colony . . 398 



D. Further development of the Cyathozooid . . . 400 



E. Development of the four primary Ascidiozooids . . 404 



5. The Hemimyaria (Salpidae) 414 



A. Forms without covering folds 423 



B. Forms with covering folds 433 



General considerations on the embryonic development 



of the Salpidae 445 



II. Asexual reproduction ......... 448 



1. Social and composite Ascidians ...... 449 



A. Reproduction through transverse fission .... 449 



B. Stolonic gemmation 455 



C. Pallial gemmation of the Botryllidae .... 458 



D. Budding of the Didemnidae and the Diplosomidae . 459 



E. Development of the organs iu asexually produced in- 



dividuals 463 



■2. Doliolidae 470 



Alternation of generations in Doliolum ..... 476 



Alternation of generations in Anchinia .... 479 



Alternation of generations in Dolchinia .... 483 



3. Pyrosoma 484 



A . Development of the proliferating stolon .... 484 



B. Further development of the buds 489 



4. Salpidae 494 



.4. Structure and development of the proliferating stolon . 495 



B. Development of the buds on the stolon .... 499 



C. Development of the organs in the bud .... 508 



5. The interpretation of the alternation of generations in the 



Tunicates 512 



III. General considerations on the Tunicates 516 



Literature 524 



