174 



NATURE 



{June 13, 1878 



and of course it would make no matter whether this 

 sporocarp were formed in the connecting canal as in 

 Mesocarpus, or whether it fills this and extends over into 

 both the cells as in Staurospermum, or as in Plagio- 

 spermum is altogether formed in one of the cells ; the 

 essential feature being the differentiation into the carpo- 

 spore and its investing covering the sporocarp. 



Now Dr. Wittrock has made the rather startling 

 observation that in one and the same species (^Mougeotia 

 calcarea, Clev.), the formation of the spores may take 

 place equally in the manner of the three above-mentioned 

 genera ; also that occasionally even the spores may be 

 formed without any conjugation, and further that in a plant 

 found growing last October in an aquatic stone house in 

 the Upsala Botanical Gardens, and which is described as 

 Gonatonema ventricosum, the spores are formed in a 

 neutral way through the agency of cells never intended 

 for and incapable of conjugation. Such spores the author 

 calls agamospores, and he finds a second species of this 

 new genus in Hassall' s anomalous Mesocarpus notabilis. 

 This memoir of Wittrock's will be found in the Bihan^iill 

 k. Svenska Vet. Akad. Handliitgar, Band 5, No. 5, 1878. 

 It is written in English, and illustrated with a plate. 

 Upon it the following observations may not seem alto- 

 gether out of place. 



If the interpretation placed on the phenomena to be 

 witnessed in the Mesocarpeae by Prof. Pringsheim be 

 accepted, then this family can scarcely be left among the 

 Conjugatae, and this would hold true also of Wittrock's 

 new genus, as indeed is so stated by himself. But may 

 not the phenomena be interpreted in yet one other way .'' 

 First, as to the agamospores in Gonatonema. Is it 

 beyond the bounds of possibility that, despite their ex- 

 ternal likeness to zygospores, these are simply vegetative 

 spores, to be compared to one of the so-called tetraspores 

 in Florideae ? They surely cannot be compared to any 

 form of organism itself the product of the commingling 

 of the contents of two different ceils ! Another sugges- 

 tion, to account for this agamospore, has been made to 

 me by my friend William Archer. It is that there may 

 have been a separation between the upper and lower 

 portions of the protoplasmic contents of the same cell, 

 and that these, without waiting for the formality of 

 forming separate cells, may have then and there con- 

 jugated. This is certainly a most ingenious suggestion, 

 and is strengthened by the well-known fact that, in some 

 Desmids, after the single-celled frond has divided into 

 two halves, and before the newer portions grow into any- 

 thing like the similitude of the older portions, the two 

 halves, which were only just parted, will conjugate and 

 form an ordinary zygospore. De Bary gives some pretty 

 figures of this strange phenomenon, which, according to 

 Mr. Archer, might be carried one step further, and there 

 be no parting at all. In favour of my own idea I can 

 only add that the first origin of what, in some of the 

 Florideas, will form the tetraspores, and the origin of 

 these agamospores, appear to me to be the same. Next 

 as to the sporocarps in Mesocarpus. The differentiation into 

 sexual entities of the protoplasmic contents of cells is con- 

 fessedly, at first, scarcely perceptible. It would be impos- 

 sible, in many cases, to say with any confidence, this one is 

 the germ cell, and that one is the sperm cell. But gradually 

 a differentiation appears in that the contents of the former 

 exhibit themselves as passive, and of the latter as active ; 

 the contents of the one remain quiescent, those of the 

 other pass over to conjugate with the former, but all 

 through the contents that commingle are almost in every 

 case alike in quantity. Carry the differentiation a step 

 further on, and we find that the contents that commingle 

 rnay be at first somewhat, and then be strikingly un- 

 like in quantity. The passive contents will be divided 

 into a comparatively small number of portions (in Fucus 

 eight), but these each can be fertilised by the very smallest 

 portion of the active contents. Now may not the Meso- I 



carpeae be a link between these groups ? The contents of 

 each of the two cells divides into certain portions. The 

 fertilising power of the active contents is not sufficient for 

 the passive contents, and hence but one portion — that the 

 most specialised — is fertilised ; this forms the zygospore ; 

 the other portions remain sterile. Then this spore would 

 differ from the zygospore of Zygnema just in the same 

 proportion as it would differ from the oospore of Fucus, 

 but the fructification would not at all be a representative 

 carpospore, and the at first sight very anomalous case of 

 M. caicarea may be explained by supposing that the 

 number of partitions is a matter of but secondaiy im- 

 portance, unless the fertilising power of the active con- 

 tents were to increase. This field of research is an 

 important one, and much as we are indebted for infor- 

 mation on these points to the labours of the Swedish 

 botanists, we must still continue to look for fresh facts 

 and new explanations. 



E. Perceval Wright 



PROF. C. F. HARTT^ 



CHARLES FREDERIC HARTT, whose death by 

 yellow fever occurred at Rio de Janeiro on the i8th 

 of last March, was born at Fredericton, New Brunswick, 

 August 23, 1840. For three years and a half before his 

 decease he had successfully withstood the fatigues of 

 exploration and the labours of organising and carrying 

 on the geological commission of Brazil, an undertaking 

 beset with many trying difficulties. 



Prof. Hartt's connection with natural history dates 

 from boyhood. Encouraged by Prof. Cheesman, he 

 made rapid progress in his favourite studies, without, 

 however, neglecting the other branches of learning. But 

 his particular bent always lay toward natural history, 

 language, music, and art. 



While a student at Acadia College, he undertook, 

 under the direction of Dr. Dawson, extensive researches 

 into the geology of Nova Scotia, which province he ex- 

 plored on foot from one end to the other. In i860 he 

 accompanied his father to St. John, there to establish a 

 college high-school. This change of location brought 

 him into another field for exploration, that of the geology 

 of New Brunswick, and he commenced his new labours 

 at once. The Devonian shales at the locality called 

 Fern Ledges, in the vicinity of St. John, were the prin- 

 cipal objects of his research. After a long siege of hard 

 work he was amply repaid by discovering an abundance 

 of land plants and insects, of which the latter stiU 

 remain the oldest known to science. Prof. Agassiz was 

 attracted by this last discovery of the young Canadian 

 naturalist, and invited him to enter his museum at Cam- 

 bridge as a student. This he did in 1861. Each vaca- 

 tion he returned, either to New Brunswick or Nova 

 Scotia, to continue his explorations. In 1864 Mr. Hartt 

 was employed, with Profs. Bailey and Matthews, on the 

 geological survey of New Brunswick, and, while en- 

 gaged in this work, obtained the first full proof of the 

 existence of primordial strata in that province. Many 

 of his discoveries in Nova Scotia and New Brunswick 

 were published in the Provincial Government reports, 

 and also in Dr. Dawson's "Acadian Geology." 



Upon the organisation of the Thayer Expedition to 

 Brazil, by Prof. Agassiz in 1865, he was appointed one of 

 its geologists, and henceforth to the time of his death he 

 was ever a most devoted investigator of South American 

 natural history. Aided by New York friends he returned 

 to Brazil alone in 1867, this time examining with the 

 greatest care the reefs of the Abroihos Islands, and those 

 of the coast, as well as the geology of a part of Bahia 

 and Sergipe. The results of his work thus far were pub- 



' From an article by Mr. R. Rathbun in the Pojinlar Science Monthly forr 

 June. 



