1032 REPORT— 1898. 



direct evidence we are thrown tack on other arguments, such as those based on 

 comparison of normal specimens, and secondly upon the study of abnormalities. I 

 shall not attempt to treat the matter exhaustively ; it will, however, be necessary 

 for me to deal with certain points in the discussion which were raised in the able 

 address of Professor Scott at Liverpool. lie there restated Pringsheim's view of 

 homologous alternation as against the antithetic. I propose now to consider three- 

 matters which I think are most material to the discussion — viz. (1) the bearing of 

 the Algaj and certain Fungi on the question ; (2) the comparison from the Bryo- 

 phyta ; and (3) the argument from abnormalities. 



I. AlgcE and Fungi. 



At first sight those Algfe and Phycomycetous Fungi which show a subdivision- 

 of the zygote appear to offer the key to tlie enigma of the first start of antithetic 

 alternation, and such rudimentary fruit-bodies as those of (Edogonium and Voleo~ 

 chwte are frequently quoted as prototypes of sporogonia. My own position has 

 been that they may be * accepted as suggestive of similar progress in the course of 

 evolution of Vascular Plants.' On the assumption that the zygote is equivalent in 

 all cases — and this is itself a pure assumption — the fruit-body of such Alga) or 

 Fungi would be comparable to the sporophyte in higher forms ; but it must be> 

 clearly remembered that it is not even then proved to be homogenetic. Dr. Scott 

 has based a strong line of criticism of antithetic views upon these cases. He 

 remarks : ' The sudden appearance of something completely new in the life-history,, 

 as required by the antithetic theory, has, to my mind, a certain improbability. 

 Ex nihilo nihil Jit. We are not accustomed in natural history to see brand new- 

 structures appearing, like morphological Melchisedeks, without father or mother. 

 Nature is conservative, and when a new organ is to be formed it is, as every one 

 knows, almost always fashioned out of some pre-existing organ. Hence I feel » 

 certain dilficulty in accepting the doctrine of the appearance of an intercalated 

 sporophyte by a kind of special creation.' 



In answer to this, I state that to me the zygote, from which our hypothesis 

 starts, is not ' nothing ; ' it is a cell with all the powers and possibilities of a com- 

 plete cell. Vochting, in his ' Organbildung,' has fairly concluded that 'a living 

 vegetative cell which is capable of growth has not a specific and unalterable 

 function.' I have mj'self demonstra-ted that cells typically sporogenous may 

 develop as vegetative tissue, and conversely that tissues normally vegetative may 

 on occasions become sporogenous. We may, therefore, say generally, as regards 

 the sporophyte, that ' a living cell which is capable of growth has not a specific 

 and unalterable function.' This I conceive to have been the condition of the 

 zygote, and of its early products. 



I think that the words ' intercalation ' or ' interpolation,' as used by writers on 

 antithetic alternation, have been quite misunderstood. I have contemplated no 

 sudden development — indeed, on the first page of my ' Studies ' I have spoken of 

 the sporophyte as ' gradually ' interpolated. Nor is the suggested development 

 something ' completely new,' for I speciHlly speak of elaboration of the zygote. 

 This is the parent of these ' morphological Melchisedeks ; ' and unless segmentation- 

 be held to be .'synonymous with ' specistl creation,' I confess I do not see where the 

 initial difficulty arises. I agree that Nature is conservative ; what we contemplate 

 is the fashioning of the sporophyte by a process of which the first step is segmen- 

 tation, out of a pre-existing organ — the zygote. Such simple segmentation is seen 

 in the case of certain Algre and Fungi, and these may be taken as suggesting how 

 the sporophyte of the Archegoniataj may have come to be initiated. But I am not 

 aware of having ever suggested that these segmented zygotes of Alga3 are the 

 homogenetic prototypes of the more elaborate sporophytes. 



Dr. Scott further states that 'the reproductive cells produced by the ordinary 

 plant of an CEdogonixnn are identical in development, structuie, behaviour, and 

 germination with those produced by the oospore.' Professor Marshall Ward, also 

 speaking of (Edogonimn, remarks ' the attempt to get over this by terming asexual 

 spores borne by the gametophyte gonidia, and reserving the term spore for bodies 

 indistinguishable from these gonidia by any morphological or physiological 



