1574 Journal of Applied Microscopy 



the round male cell becomes elongated, one figure showing it spirally wound, 

 but this may not be the normal form. In Taxodium, however, the spiral form is 

 the usual one, and this is probably the case in the Cupressineae also. The form 

 is probably due to the narrow entrance, the male cell having a greater diameter 

 than the neck of the archegonium. The behavior of the chromatin during 

 fertilization is not described. 



In Sequoia sempervi reus the. sex nuclei fuse at the middle of the archegonium, 

 then sink to the bottom and divide. Two cells are organized about the nuclei 

 and the lower nucleus divides again, thus giving rise to a row of three cells, the 

 lowest of which becomes the embryo and the middle the suspensor. The upper 

 soon disorganizes and at this stage the embryo appears to consist of two cells. 

 The first division of the embryo is longitudinal. In Cryptomeria and Taxodium 

 the fertilized egg nucleus passes to the base of the archegonium, where two or 

 three divisions occur. Cells are formed about the lower nuclei, but the upper 

 ones remain free. Two or three tiers are organized, the lower one or two tiers 

 forming the embryo, and the tier next above, the suspensor. This agrees with 

 Strasburger's diccouwt oi /iinipenis, except that the free cells were not described. 

 Cunninghamia agrees with Taxodium, Cryptomeria and the Cupressineae. In 

 Sciadflpifys, the series was very incomplete, but enough was obtained to show 

 that the embryology is very peculiar. The earliest stage found shows four free 

 nuclei at the base of the archegonium, as in all the Abietineae. A later stage 

 shows a " rosette," suspensors, and a loose tissue of embryonic cells. The lowest 

 of these cells form the embryo, those next above develop into a second set of 

 suspensors, still leaving some of the embryonic cells between the two suspensor 

 systems. The figures bear some resemblance to Strasburger's figures oiAraucaria, 

 but in Strasburger's account the second set of suspensors, as described by 

 Arnoldi, form a cap which is cast off while the part between the two suspensor 

 systems — or between the suspensor and cap — develops into the embryo. 



Arnoldi believes that the two species of Sequoia should constitute a family, 

 the Sequoiaceae ; that Taxodium, Cryptomeria and, perhaps, Cunninghamia 

 should be included in the Cupressineae ; and that Sciadopitys is best regarded as 

 constituting a special family, the Sciadopiteae. c. j. c. 



Livingston, B. E. On the Nature of the The effect of external osmotic pressure 



Stimulus which Causes the Change of Form upon green algae has recently been 

 in Polymorphic Green Aleae. Bot. Gaz. j ^i i • ^ /• • .• .- i 



30: 289-317, pis. 17-18, 1901. i^ade the subject of an mvestigation by 



B. E. Livingston. A polymorphic form 

 of Stigeoclonium was chosen. Knop's solution was used as a nutrient medium. 

 In a weak solution (up to 0.1 per cent.) swarm spores are produced in 

 great numbers which germinate to form branching filaments. In a 

 solution whose concentration is 0.5 per cent, to '1 per cent, no swarm 

 spores are produced, but the cells grow and multiply by divisions in all directions, 

 the daughter cells separating almost as soon as formed. This process results in 

 a mass of rounded cells like those of Palmclla. If filaments are placed in the 

 stronger solution their cells change from the cylindrical to the spherical form 

 and break apart. In solutions of intermediate strengths, swarm spores may be 



