K.—BOTANY. 185 
instructive. He points out that ‘it occupies the least area of the sub- 
stratum,’ that this allows ‘ indefinite gregarious association’ ; and that it 
extends ‘ longitudinally to the limit of mechanical cohesion and hapteron- 
system ’"—“ Individuals may thus attain in quiet waters a range of 40 ft., 
while the filamentous soma gives little more range than 1 ft.’ 
4. The Corticated Type.—In this are included Stilophora, Spermatochnus, 
Arthrocladia, &c., together with the well-known Desmarestia. The latter 
has an axis consisting simply of branching, uniseriate filaments with 
“trichorhallic’’ growth, but completely obscured by a massive develop- 
ment of pseudoparenchyma, due to the growth of descending ramuli. 
This bulky tissue may show some amount of differentiation, and the 
success of the strengthening device enables the plants to reach a length of 
4 to 6 ft. In summer the plants bear tufts of delicate branches which are 
_ shed again before winter—a seasonal adaptation resembling that obtaining 
in our deciduous trees. 
. 5. The Parenchymatous Type including laminate forms like Punctaria 
as well as tubular types like Asperococeus ; and derivable from a Chorda- 
like type by suppression of external ramalia, localisation of sori, and 
immersion of reproductive structures in the parenchymatous thallus. 
The author maintains that ‘there can be no doubt, so far, that sorus- 
location is always to be taken as the indication of a preceding condition 
of diffused production of similar ramalia-systems.’ 
_ 6. Improved Parenchymatous Types—These, culminating in the 
_ Pucacee and the Laminariacee, and presenting a surprising variety of 
; forms, with a high degree of differentiation of members, and an elaboration 
_ of tissue-systems far in advance of anything known in any other group of 
_ the Thallophyta, are far too well known to need description. The author’s 
treatment of the factors concerned in the evolution of the various forms 
and their morphological significance is exhaustive and interesting. He 
adds equally instructive accounts of various reduced forms, parasites and 
J endophytes. 
_ Among the structures about which further information is much needed 
var the characteristic Laminarian ‘Trumpet-hyphe.’ Wille? published a 
_ drawing of these structures in Laminaria Cloustoni and he showed the 
perforated sieveplate, but not the thickenings of the walls—like many 
others, he regarded them as artifacts. Oliver ? demonstrated the presence, , 
nature and origin of the callus often found in them, and incidentally 
described the walls as being ‘ striated.’ These markings, however, do not 
appear in the drawings. Miss Sykes (Mrs. Thoday),* employing the methods 
_ of Gardiner and Hill, proved that the crosswalls in these structures were 
true sieveplates traversed by slime-strings enclosed in callus rods. Owing 
to the swelling method employed, the thickenings could not be seen. 
_ Later she expressed the opinion that they were artifacts. Previous to this, 
- Rosenthal® had figured the ‘spiral thickenings’ in Laminaria, and finding 
_ them also in Chorda (of which Reinke® published drawings in the following 
year), he made the pertinent suggestion that this fact should weigh in 
2 Ber. d. deutsch. bot. Ges., 1885. 
8 Ann, of Bot. i., 1887. 
4 Tbid. xxii, 1908. 
5 Flora, 1890. 
6 Atlas deutsch. Meeresalgen, 1891. 
