Henry Harold Welch Pearson. 141 
His paper on the subject communicated to the Eoyal Society of London 
may well be regarded as his masterpiece. It is here that he cleverly dis- 
posed of a puzzling and troublesome structure by his term " trophophyte." 
In like manner in his first paper, also communicated to the Royal Society, 
he was responsible for introducing the term " prothalial-tube." 
At this time, when he was so actively engaged in the histological study 
of the endosperm of Welwitschia, he had naturally taken advantage of the 
enthusiasm which he had instilled into his more promising students to pro- 
secute research of a similar nature amongst other South African genera, 
and during this time a series of papers dealing with the development of 
the embryo- sac appeared. 
Pearson's observations on Welwitschia at once raised many points with 
regard to its alliance with Gnetum and their affinity to the Angiosperms. 
Both these phases he entered into fully, and even predicted that Gnetum 
would show similar fertilisation phenomena as pertained in Welwitschia. 
Having disposed of the botanical details of the fertilisation of Wel- 
witschia, Pearson with characteristic thoroughness turned his attention to 
Gnetum. Here again the first step that he undertook was a study of the 
life-history of Gnetum. africamim. With this object in view he visited 
Angola in 1909, and obtained material for such an investigation as he had 
previously carried out on Welwitschia. 
From his examination of Gnetum africanum and two other species he 
concluded that Gnetum showed a much closer degree of affinity with Wel- 
witschia than with Ephedra. His first paper left many interesting points 
in connection with the male gametophyte still to be cleared up. By this 
time Gnetum was being examined by several workers, and l^efore Pearson's 
second paper on Gnetum dealing with the morphology of the inflorescence 
and flower appeared, Thompson in America published the results of his 
examination of the embryo-sac and male gametophyte, from which it was 
evident that the conditions in Gnetum resembled those in Welwitschia, as 
Pearson had many years before predicted, 
Pearson, however, had not been slow in unravelling the puzzling and 
difficult histological details connected with the reproduction of Gnetum, for, 
in his paper presented to the Linnean Society on June 4, 1914, he showed 
very clearly that " the primary endosperm of Gnetum is in all respects 
homologous with the primary endosperm of Welwitschia,'' and his sugges- 
tions that such fertilisation phenomena might be associated with the polar 
nuclei in Angiosperms have given rise to much reasonable discussion and 
speculation on these points. 
Two further papers on Gnetum were written by Pearson prior to his 
death, and are as yet still in the press. 
Pearson, in his travels in South-West Africa, did not confine himself to 
the mere collection of material for further study in the la])oratory or com- 
