i8o Drew .— The Reproduction and early Development of 
of the smaller Algae grow with comparative ease ; species of the Ecto- 
carpaceae in particular grow so readily that they soon tend to cover any 
undisturbed spot where the light is sufficiently powerful for their needs. 
The water which circulates in the Laboratory is drawn from Plymouth 
Sound, allowed to clear in a settling tank, and then pumped through 
vulcanite pipes into the tanks. The same supply of water may be used 
again and again for several weeks. 
The most obvious physical difference between the artificial and natural 
environment is the absence of wave motion in the former. Acting on this 
suggestion, the action of the waves was imitated as far as possible by keep¬ 
ing the plants slowly and continuously in motion in a tank with free 
circulation of water, and by avoiding overcrowding. The plants were tied 
by their roots to a weighted glass rod which was connected with the ‘ stir¬ 
ring ’ apparatus of the Laboratory. This consists of a siphon which 
automatically fills and discharges about once a minute, and so raises and 
lets fall a heavy float. The range of motion is about two feet, and the 
power is distributed throughout the Laboratory by a system of wires and 
pulleys, so that it can be used where required. By this means the plants 
were kept in a healthy condition for some months, and cultures were 
successfully made from the reproductive areas, though the whole thallus 
in time tended to become covered by a free growth of various species of 
Ectocarpus . This method of keeping the plants alive was first adopted 
in November, and in the following July young Laminaria plants, from one- 
quarter to half an inch in length, were found growing attached to the sides 
of various tanks, some of them at a considerable distance from the tank in 
which the experiments were conducted. Young Laminaria plants had 
never before been observed growing naturally in the Aquarium. 
Examination of the reproductive areas. 
Sections are best cut by the freezing method. If any process involving 
treatment with alcohol be used, the resulting dehydration produces a shrink¬ 
ing of the mucilaginous contents of the cells which results in considerable 
distortion. No fixing agent was found which would prevent this change. 
A good fixative for use before cutting sections by the freezing method 
is a saturated solution of picric acid in sea-water ; this should be allowed to 
act for at least twenty-four hours. Almost equally good results are obtained 
by the use of a 2 per cent, solution of 40 per cent, formalin in sea-water. 
A satisfactory staining method for sections is the following:— 
1. Stain for one minute with Loffler’s methylene blue solution, 
undiluted. 
2. Decolorize by successive washings with acid alcohol, until only 
the extreme edges of the section retain the stain. 
3. Counterstain with very dilute safranin. 
