62 W. WOODLAND. 



retained its relative position in the organism (for- 

 mation of evaginations of the separate enteron in Balano- 

 glossus to meet the stomodteal and proctodffial invaginations 

 of the epiblast^ etc.). Including these apparently anomnlous 

 cases, it is one of the most certain facts in Biology that if a 

 detached cell (or cells) is to produce an organ of the adult 

 organism, it must become connected with its fellows.^ And 

 as I have pointed out above, the hypothesis of the inherit- 

 ance of spicule forms denies this. 



The above argument, however, strictly speaking, solely 

 applies to spicules adapted in form to the architecture of the 

 organism (most of the large complicated spicules), but many 

 spicules exist which exhibit no such relationship (micro- 

 scleres of siliceous sponges, stellate spicules of Ascidians, 

 many holothurian and alcyonarian spicules, etc.) But even 

 in this case the scleroblasts will be unique amongst 

 wandering-cells if they produce by heredity an internal 

 spicule-mould (often also, as just stated, undergoing disten- 

 sion and external change of form), i.e. if they assume a 

 complicated structure." Apart from this very hypothetical 

 case of the scleroblasts I know of no instance of wandering- 

 cells becoming complicated in form at all. Spermatozoa are 

 cells separated off from the rest of the organism, and which 

 become very complex in structure, but this complexity (defi- 

 nitely related to a function) arises in the cell before it is 

 detached, and is analogous to the production of the ciliated 

 cells of a Vorticella or of meduste from a hydrozoan colony; 



1 Prof. Dendy has kindly brought to my notice the following striking 

 illustration of my argument. Lefevre ("Jour. Morph.," 1898), in a paper 

 on "Budding in Perophora," states that wandering cells (free blood-cells) 

 produce tlie lieart, neural ganglion, gonads, and some other organs of the 

 buds, but in order to do this they must become closely attaciied to 

 the organism. As I iiave argued in the text, cells wliich remain free 

 either become wandering cells or, as shown, e.g. by the redise and cercarise of 

 the common Distomurn, produce miniature organisms. 



^ The mere idea of a wandering cell possessing tlie capacity to form an 

 internal mould of the complexity required for the production of a hexacti- 

 nellid floricome or onychaster, e.g. seems absurd. 



