336 BOTANICAL GAZETTE [OCTOBER 
hybridization, but that pollen sterility is a physiological condition which may 
be due to a variety of causes, hybridization and mutability being only two of 
them.—J. M. C 
Codium mucronatum.—Miss Hurp' has made a study of Codium mucro- 
natum from Puget Sound material, to establish the characteristics on the basis 
of which this species may be distinguished from other species, and to determine 
whether the division of this species into varieties poliney J. G. Agardh 
and novaezelandiae J. G. Agardh) is justified. The study is a careful one and 
the plates will prove valuable to students of this genus. She suggests a detailed 
description for the species and concludes that the splitting of the species into 
varieties on the basis of the mucoronate tips of the utricles is not justified, 
since all of the described types are often found on the same plant.—GerorcGE B. 
RIGG. 
Réntgen rays.—KoOERNICKE* finds that a small dosage of Réntgen rays 
accelerates growth of seeds and seedlings. In larger amounts it has no effect, 
while in still larger amounts it inhibits growth. In this regard Rontgen rays 
act like other rays and like toxic materials in general. Vicia Faba was especially 
favorable material for experimentation. Contrary to the claims of SCHWARZ, 
the effect of a stimulative dose at the seed or seedling stage was lost before 
maturity was reached. From the results of ScowARZ, KOERNICKE had thought 
that Réntgen rays might be applied profitably in practice for increasing yield, 
but his work shows that this is not the case—WILLIAM CROCKER. 
Trigonocarpus and Ginkgo.—In 1914 SALISBURY? published an account 
of a new species of Trigonocarpus, and compared it with the seeds of Ginkgo. 
Later, Miss Arrourtir and Miss LA Riviére* investigated the seeds of 
Ginkgo and gave reasons for the belief that such a comparison is not valid. 
SALISBURY 55 has published a brief note in reply, pointing out more specifically 
the reasons for his view, and concludes that in the more important features 
of general organization the ovules of Ginkgoales, Cycadales, and Trigonocarpus 
exhibit a peorieel of construction difficult to explain except on the basis 
of affinity —J. M 
3* Hurp, ANNIE M., Codium mucronatum. Puget Sound Marine Sta. Publ. 1: 
109-135. pis. 19-24. 1916. 
# Korrnicxe, M., Uber die Wirkung verschieden starker Réntgenstrahlen auf 
Keimung und Wachstum bei den héheren Pflanzen. Jahrb. Wiss. Bot. 56:416~430- 
1915. P¥FEFFER’Ss Festschrift. 
3 Review in Bor. Gaz. 57:440. 1914. 
34 Review in Bot. Gaz. 61:176. 1916. 
3s SatisBuRY, E. J., On the relation between Trigonocarpus and Ginkgo. Ann. 
Botany 30:356. 1916. 
