Dr. R. Greeff on Autolytus prolifer. 177 
free offspring (Sacconereis and Polybostrichus).and the primary 
individuals of Auwtolytus. In his first memoir (Wiegmann’s 
Archiv, 1852) he not only correctly described the female Sac- 
conereis, but also the male, indicating especially the charac- 
teristic and different structure of the tentacles of the male. 
He says (p. 70), ‘On the other hand, in the male, the two 
lateral tentacles are furcately divided into two diverging 
branches, one of which is shorter than the other.” In his 
second communication (Miiller’s Archiv, 1855, p. 489) he 
definitely indicates the origin of Max Miiller’s genus Sacco- 
nereis from Autolytus. I have myself repeatedly observed 
the whole of the forms just mentioned, and can confirm their 
mutual relation in the most positive manner, although I 
have made some divergent observations upon the mode of 
prolification. In his description of the structure of the 
bud-sprouts (/.c. p. 74) Krohn says that, with the exception 
of the first offspring at the hinder extremity of the parent 
animal, produced at the expense of the hinder part of the 
body of the mother (as, according to Leuckart and Frey, the 
buds are produced only between the anterior and posterior 
sections of the body, z. e. push themselves in between these), 
and which is therefore a true product of fission, ova and 
semen are not produced in any of the individuals subsequently 
developed from buds, until at least the head with the traces of 
the eyes and tentacles has been formed. I have had examples 
under my eyes in which above the youngest sprout (which 
therefore hung next to the parent animal) some segments of 
_ the primary body already contained ova, although not the 
sinallest trace of head &c. could be detected either upon or 
above these segments. Ina case represented exactly in PI. VIII. 
fig. 2, the hinder female sprout was already completely deve- 
loped, with its head and three tentacles, and had its two fol- 
lowing segments stuffed with ova, so that the second body- 
segment had acquired an unusual degree of extension. But 
the last segments of the primary animal impinging on the head 
of the sprout also already contained ova, although no formation 
of a head kc. could be detected. It is therefore evident that 
the above statement of Krohn’s cannot be maintained in its 
universality. But our observation also imports a not unim- 
portant modification into our notion of the mode of reproduc- 
tion, as this case proves not only that the fully developed 
sprouts are capable of producing ova &c., as has hitherto been 
assumed with regard to Awtolytus, but that ova may be pro- 
duced even in the parent body (that is to say, in the nurse 
itself), and, indeed, in segments which still belong to it entirely 
and unchanged, as has already been ascertained in the case of 
